Missouri: Consolidated Chronology of State and County Boundaries

Missouri Atlas of Historical County Boundaries

John H. Long, Editor; Peggy Tuck Sinko, Associate Editor and Historical Compiler; Douglas Knox, Book Digitizing Director; Emily Kelley, Research Associate; Laura Rico-Beck, GIS Specialist and Digital Compiler; Peter Siczewicz, ArcIMS Interactive Map Designer; Robert Will, Cartographic Assistant

Copyright The Newberry Library 2007

30 April 1803

The United States purchased Louisiana from France, taking formal possession on 20 December 1803; boundaries were not clearly defined, but included the western half of the Mississippi drainage basin (from the Mississippi R. to the Rocky Mts.). (Parry, 57:27-40; Van Zandt, 23-26)

1 October 1804

The United States created the District of Louisiana from the part of the Louisiana Purchase north of 33 degrees north latitude, the limit of the present state of Louisiana (then New Orleans Territory); the district was not fully organized as a territory and was attached to Indiana Territory. (Terr. Papers U.S., 13: 51-52; U.S. Stat., vol. 2, ch. 38 [1804]/pp. 283-289; Violette, 46-47)

Five districts were created within the District of Louisiana: Ste. Genevieve District (now STE. GENEVIEVE); St. Louis District (now ST. LOUIS); St. Charles District (now ST. CHARLES); New Madrid District (now NEW MADRID); Cape Girardeau District (now CAPE GIRARDEAU). (Terr. Papers U.S., 13: 51-52; U.S. Stat., vol. 2, ch. 38 [1804]/pp. 283-289; Violette, 46-47)

4 July 1805

District of Louisiana renamed Louisiana Territory and detached from Indiana Territory; the territory included all of present Missouri. (U.S. Stat., vol. 2, ch. 31[1805]/pp. 331-332)

1 July 1806

New Madrid District (now NEW MADRID) gained from Cape Girardeau District (now CAPE GIRARDEAU). (Terr. Papers U.S., 13:541-542; Gov. Proc. 7 June 1806)

15 August 1806

Cape Girardeau District (now CAPE GIRARDEAU) gained from New Madrid District (now NEW MADRID). (Ford, 5-6)

7 December 1812

Louisiana Territory renamed Missouri Territory. Cape Girardeau District became CAPE GIRARDEAU County; New Madrid District became NEW MADRID County; St. Charles District became ST. CHARLES County; St. Louis District became ST. LOUIS County; Ste. Genevieve District became STE. GENEVIEVE County. (Terr. Papers U.S., 14:599-601; U.S. Stat., vol. 2, ch. 95[1812]/pp. 743-747)

Non-County Area 1 created from CAPE GIRARDEAU, NEW MADRID, ST. LOUIS, and STE. GENEVIEVE, when their western boundaries were redefined as the boundary of the "Osage Purchase". (Royce, 676-677, pls. 112, 144; Terr. Papers U.S., 14:599-601)

1 November 1813

WASHINGTON created from ST. LOUIS and STE. GENEVIEVE. (Mo. Terr. Laws 1813-1814, ch. 95, secs. 1,11/pp. 285-290; Violette, 78)

31 December 1813

Missouri Territory passed a single law adjusting the boundaries of 7 counties and 2 non-county areas. (Mo. Terr. Laws 1813-1814, ch. 99, sec. 1/pp. 293-295)

1 March 1815

LAWRENCE (original) created from NEW MADRID; included parts of present Missouri and Arkansas. (Mo. Terr. Laws 1814-1815, ch. 128, secs. 1, 9/pp. 354-357)

9 March 1815

ST. CHARLES gained from Non-County Area 2. (Terr. Papers U.S., 15: 40-41)

1 March 1816

HOWARD created from ST. CHARLES and ST. LOUIS. (Mo. Terr. Laws 1815-1816, ch. 162, secs. 1, 8/pp. 460-464)

20 October 1818

Non-County Area 2 exchanged with British North America when a Convention of Commerce between Great Britain and the United States established 49 degrees north latitude, from the Lake of the Woods to the Rocky Mountains, as the northern boundary of the United States, and the southern boundary of the British possessions. (Parry, 69: 294-297)

1 January 1819

FRANKLIN created from ST. LOUIS. (Mo. Terr. Laws 1818-1819, ch. 225, secs. 1, 8/pp. 562-566)

JEFFERSON created from ST. LOUIS and STE. GENEVIEVE. (Mo. Terr. Laws 1818-1819, ch. 220, secs. 1, 10/pp. 554-558)

LINCOLN created from ST. CHARLES. (Mo. Terr. Laws 1818-1819, ch. 228, secs. 1, 8/pp. 572-576)

MADISON created from CAPE GIRARDEAU and STE. GENEVIEVE. (Mo. Terr. Laws 1818-1819, ch. 229, secs. 1, 8/pp. 576-580)

MONTGOMERY, and Non-County Area 3 created from ST. CHARLES; Non-County Area 3 attached to MONTGOMERY "for judicial, probate, administration and county purposes." (Mo. Terr. Laws 1818-1819, ch. 230, secs. 1, 8/pp. 580-584)

1 February 1819

COOPER created from HOWARD. (Mo. Terr Laws 1818-1819, ch. 233, secs. 1, 10/pp. 594-598)

PIKE created from ST. CHARLES. (Mo. Terr. Laws 1818-1819, ch. 231, secs. 1, 8/pp. 585-588)

WAYNE created from CAPE GIRARDEAU, LAWRENCE (original), and NEW MADRID. Unattached Non-County Area 4 created from strip of land remaining from former western boundary of CAPE GIRARDEAU. (Mo. Terr. Laws 1818-1819, ch. 226, secs. 1, 10/pp. 567-571)

22 February 1819

Non-County Area 1 exchanged with Spain as a result of the Adams-Onis Treaty with Spain on 22 February 1819. (Mo. Terr. Laws 1813-1814, ch. 99, sec. 1/pp. 293-295)

1 June 1819

CLARK (Ark.), HEMPSTEAD (Ark.), and PULASKI (Ark.) created from ARKANSAS (Ark.) and Non-County Area 1; all included territory in present Arkansas and Oklahoma. Non-County Area 1 gained from ARKANSAS (Ark.). Quapaw Indian Reservation was not included within any county jurisdiction. (Mo. Terr. Laws 1818-1819, ch. 232a/secs. 1-3, 5/pp. 589-591)

4 July 1819

The United States created Arkansas Territory from that part of Missouri Territory south of the parallel of 36 degrees, 30 minutes north latitude; ARKANSAS (Ark.), CLARK (Ark.), HEMPSTEAD (Ark.), and PULASKI (Ark.) became Arkansas Territory counties. NEW MADRID exchanged with Arkansas Territory; the southern part of LAWRENCE (original), part of Non-County Area 1, and all of the Quapaw Indian Reservation became part of Arkansas Territory. (U.S. Stat., vol. 3, ch. 49[1819]/pp. 493-496)

6 March 1820

The United States authorized creation of the state of Missouri from Missouri Territory, establishing the northern boundary of the proposed state as the present boundary between Iowa and Missouri from the Des Moines River to the intersection of the Kansas and Missouri Rivers [not mapped]. (U.S. Stat., vol. 3, ch. 22[1820]/pp. 545-548)

1 January 1821

BOONE, RAY, Non-County Area 5, and Non-County Area 7 created from HOWARD; CHARITON and Non-County Area 6 created from HOWARD and PIKE; Non-County Area 2 gained from HOWARD and PIKE. Non-County Area 5 attached to BOONE; Non-County Area 6 attached to CHARITON; Non-County Area 7 attached to RAY. All attachments "for all legislative, judicial, and military purposes." (Mo. Laws 1820-1821, ch. 14, secs. 1-5/pp. 21-26)

CALLAWAY created from Non-County Area 3; remainder of Non-County Area 3 detached from MONTGOMERY and attached to CALLAWAY for administrative and judicial purposes. (Mo. Laws 1820-1821, ch. 29, secs. 1, 8/pp. 52-55)

COLE created from COOPER. (Mo. Laws 1820-1821, ch. 16, secs. 1, 11/pp. 31-34)

GASCONADE, and Non-County Area 8 created from FRANKLIN; Non-County Area 8 attached to GASCONADE "for all civil, military, and judicial purposes." (Mo. Laws 1820-1821, ch. 28, secs. 1-2, 5/pp. 51-52)

LILLARD (extinct) created from COOPER and Non-County Area 1. (Mo. Laws 1820-1821, ch. 10, secs. 1, 6/pp. 13-15)

PERRY created from STE. GENEVIEVE. (Mo. Laws 1820-1821, ch. 15, secs. 1, 10/pp. 27-31)

RALLS, and Non-County Area 9 created from PIKE. (Mo. Laws 1820-1821, ch. 12, secs. 1, 4/pp. 17-18)

SALINE created from COOPER. (Mo. Laws 1820-1821, ch. 27, secs. 1, 11/pp. 48-51)

10 August 1821

The state of Missouri was created from Missouri Territory, with all modern boundaries, except for the northwestern corner of the present state, which became unorganized federal territory. The following became counties in the state of Missouri: BOONE, CALLAWAY, CAPE GIRADEAU, FRIANKLIN, GASCONADE, HOWARD, JEFFERSON, LAWRENCE (original), LILLARD (extinct), LINCOLN, MADISON, MONTGOMERY, NEW MADRID, PERRY, PIKE, RALLS, RAY, ST. CHARLES, ST. LOUIS, STE. GENEVIEVE, SALINE, WASHINGTON, and WAYNE. Most of Non-County Area 1 became unorganized federal territory and Non-County Area 2 was eliminated. (Terr. Papers U.S., 15:742-744; U.S. Stat., vol. 3, ch. 22[1820]/pp. 545-548)

19 December 1821

ST. FRANCOIS created from JEFFERSON, STE. GENEVIEVE, and WASHINGTON. (Mo. Laws 1821-1822, ch. 26, sec. 1/pp. 28-30)

2 January 1822

BOONE gained all of Non-County Area 5; Non-County Area 5 eliminated. (Mo. Laws 1821-1822, ch. 36, sec. 1/p. 58)

CLAY created from RAY, and from part of Non-County Area 7 attached to RAY. (Mo. Laws 1821-1822, ch. 39, sec. 1/pp. 60-62)

1 March 1822

SCOTT created from NEW MADRID. (Mo. Laws 1821-1822, ch. 28, secs. 1, 8/pp. 32-36)

28 November 1822

Boundary between NEW MADRID and SCOTT redefined [no discernible change]. (Mo. Laws 1822, ch. 9, secs. 1-2/p. 15)

14 December 1822

MARION and Non-County Area 10 created from RALLS; both MARION and Non-County Area 10 attached to RALLS "for all military, civil, and judicial purposes." (Mo. Laws 1822, ch. 38, secs. 1-3/pp. 61-62)

26 May 1824

The unorganized federal territory (northwestern corner of present Missouri) gained from Arkansas Territory. (U.S. Stat., vol. 4, ch. 155 [1824]/pp. 40-41)

30 December 1824

SCOTT gained from CAPE GIRARDEAU. (Mo. Laws 1824-1825, pub., ch. 9, secs. 1-2/p. 11)

14 January 1825

GASCONADE gained from Non-County Area 8. (Mo. Laws 1824-1825, pub., ch. 11, sec. 1/pp. 13-15)

22 January 1825

Non-County Area 11 created from FRANKLIN and attached to FRANKLIN "for administrative and judicial purposes." (Mo. Laws 1824-1825, pub., ch. 14, sec. 9/pp. 16-19)

16 February 1825

Missouri Legislature passed a single law creating or adjusting the boundaries of 17 counties and 9 non-county areas. (Mo. Laws Rev., 1825, ch.1; for sections on particular counties see following citations):

15 December 1826

JACKSON fully organized, detached from LAFAYETTE. (Mo. Laws 1826-1827, ch. 20, sec. 1/pp. 30-31)

23 December 1826

RALLS gained from MARION; MARION fully organized, detached from RALLS; Non-County Area 10 detached from RALLS, attached to MARION "for all military, civil, and judicial purposes." (Mo. Laws 1826-1827, ch. 31, secs. 1-2, 8/pp. 40-41)

6 May 1828

The unorganized federal territory gained when the western boundary of Arkansas Territory was redefined in a treaty with the Cherokee. (U.S. Stat., vol. 7 [1828]/pp. 311-315; Van Zandt, 119)

12 January 1829

Non-County Area 15 created from SALINE, attached to SALINE "for all purposes, civil and military." (Mo. Laws 1828-1829, ch. 58, sec. 102/pp. 70-71)

16 January 1829

RALLS gained from PIKE. (Mo. Laws 1828-1829, ch. 60, sec. 1/p. 72)

STODDARD created from CAPE GIRARDEAU, NEW MADRID, SCOTT, and WAYNE; STODDARD not fully organized, attached to CAPE GIRARDEAU "for all civil and military purposes." (Mo. Laws 1828-1829, ch. 59, secs. 1-3/pp. 71-72)

22 January 1829

RANDOLPH created from RALLS and Non-County Area 6; CHARITON gained from Non-County Area 6; Non-County Area 6 detached from CHARITON and attached to RANDOLPH "for all civil and military purposes." (Mo. Laws 1828-1829, ch. 29, secs. 1-2, 7/pp. 42-44 and ch. 30, sec. 1/p. 44)

23 January 1829

CRAWFORD created from Non-County Area 8 attached to GASCONADE; Non-County Area 8 eliminated. (Mo. Laws 1828-1829, ch. 19, sec. 1/p. 23)

4 January 1831

CRAWFORD gained from WAYNE and Non-County Area 11; Non-County Area 16 created from CRAWFORD. (Mo. Laws 1830-1831, pub., ch. 14, sec. 1/p. 21)

6 January 1831

MONROE created from RALLS and Non-County Area 10; Non-County Area 17 created from RALLS; Non-County Area 17 attached to MONROE "for all civil, judicial, and military purposes." (Mo. Laws 1830-1831, pub., ch. 15, secs. 1, 6/pp. 21-22)

12 January 1831

AUDRAIN created from RALLS, Non-County Area 3, and Non-County Area 17; AUDRAIN not fully organized, parts attached to CALLAWAY, MONROE, and RALLS "for all civil and military purposes." (Mo. Laws 1830-1831, pub., ch. 13, secs. 1-2/p. 20)

RIPLEY created from WAYNE; RIPLEY not fully organized, attached to WAYNE "for all civil and military purposes"; Non-County Area 16 gained from WAYNE. (Mo. Laws 1830-1831, pub., ch. 19, secs. 1-3/pp. 26-27)

18 January 1831

Non-County Area 16 attached to CRAWFORD "for all civil and military purposes." (Mo. Laws 1830-1831, ch. 93, p. 115)

1 February 1831

Boundary between JEFFERSON and STE. GENEVIEVE clarified [no change]. (Mo. Laws 1830-1831, pub., ch. 17, sec. 3/pp. 24-25 and Mo. Laws 1832-1833, pub., ch. 34, sec. 2/p. 57)

2 January 1833

CARROLL, and Non-County Area 18 created from Non-County Area 7; Non-County Area 18 attached to CARROLL "for all civil, judicial and military purposes." (Mo. Laws 1832-1833, pub., ch. 24, secs. 1, 5/pp. 46-47)

CLINTON created from Non-County Area 12; remainder of Non-County Area 12 detached from CLAY and attached to CLINTON "for all civil, judicial, and military purposes." (Mo. Laws 1832-1833, pub., ch. 25, secs. 1, 6/pp. 47-48)

GREENE created from Non-County Area 16. (Mo. Laws 1832-1833, pub., ch. 26, sec. 1/p. 49)

LEWIS, and Non-County Area 19 created from Non-County Area 10; Non-County Area 19 attached to LEWIS "for all civil, judicial, and military purposes." (Mo. Laws 1832-1833, pub., ch. 28, secs. 1, 6/pp. 51-52)

5 January 1833

MORGAN created from COOPER, CRAWFORD, and Non-County Area 15. (Mo. Laws 1832-1833, pub., ch. 29, sec. 1/pp. 52-53)

RIPLEY gained from Non-County Area 13; Non-County Area 13 eliminated. RIPLEY fully organized, detached from WAYNE. (Mo. Laws 1832-1833, pub., secs. 1-2/pp. 55-56 and ch. 33, sec. 1/pp. 56-57)

WARREN created from MONTGOMERY. (Mo. Laws 1832-1833, pub., ch. 95, sec. 1/pp. 126-128)

16 January 1833

BATES created from JACKSON, LAFAYETTE, and Non-County Area 16; BATES not fully organized, attached to JACKSON "for all civil and military purposes." (Mo. Laws 1832-1833, pub., ch. 27, sec. 3/p. 50)

ST. CLAIR created from LAFAYETTE, Non-County Area 15, and Non-County Area 16; ST. CLAIR not fully organized, attached to GREENE "for all civil and military purposes." (Mo. Laws 1832-1833, pub., ch. 27, sec. 4/p. 51)

ST. FRANCOIS gained from WASHINGTON. (Mo. Laws 1832-1833, pub., ch. 34, sec. 1/p. 57)

VAN BUREN (now CASS) created from JACKSON and LAFAYETTE; VAN BUREN not fully organized, attached to JACKSON "for all civil and military purposes." (Mo. Laws 1832-1833, pub., ch. 27, sec. 2/p. 50)

19 January 1833

PULASKI created from CRAWFORD and MORGAN. (Mo. Laws 1832-1833, pub., ch. 31, sec. 1/pp. 54-55)

26 January 1833

PETTIS created from COOPER, MORGAN, ST. CLAIR, SALINE, and Non-County Area 15. Non-County Area 15 eliminated. (Mo. Laws 1832-1833, pub., ch. 30, sec. 1/pp. 53-54)

28 June 1834

Unorganized federal territory lost to Michigan Territory. (Terr. Papers U.S., 12:778-779; U.S. Stat., vol. 4, ch. 98 [1834]/p. 701)

3 December 1834

Non-County Area 20 created from PETTIS. (Mo. Laws 1833-1834, pub., p. 416)

13 December 1834

JOHNSON created from VAN BUREN (now CASS) and LAFAYETTE. (Mo. Laws 1834-1835, priv. and loc., pp. 37-38)

RIVES (now HENRY) created from LAFAYETTE and a small portion of Non-County Area 16. (Mo. Laws 1834-1835, priv. and loc., pp. 37-38)

2 January 1835

SHELBY created from Non-County Area 10. (Mo. Laws 1834-1835, priv. and loc., p. 40)

STODDARD exchanged with CAPE GIRARDEAU, NEW MADRID, and WAYNE; STODDARD fully organized, detached from CAPE GIRARDEAU. (Mo. Laws 1834-1835, priv. and loc., pp. 39-40)

3 January 1835

BENTON created from ST. CLAIR, Non-County Area 16, and Non-County Area 20; ST. CLAIR gained from Non-County Area 20. Non-County Area 20 eliminated. (Mo. Laws 1834-1835, priv. and loc., pp. 41-42)

5 January 1835

BARRY created from GREENE. POLK created from GREENE, PULASKI, ST. CLAIR, and Non-County Area 16. (Mo. Laws 1834-1835, priv. and loc., pp. 42-43)

26 January 1835

PULASKI gained from GREENE and Non-County Area 16, exchanged with RIPLEY; MORGAN gained from PULASKI; Non-County Areas 21 and 22 created from PULASKI. (Mo. Laws 1834-1835, priv. and loc., pp. 15-16)

11 February 1835

ST. CLAIR detached from GREENE, attached to RIVES (now HENRY) "for all civil and military purposes." (Mo. Laws 1843-1835, priv. and loc., p. 47)

17 February 1835

Non-County Area 16 detached from CRAWFORD, attached to BENTON "for all civil and military purposes." (Mo. Laws 1834-1835, priv. and loc., p. 47)

3 March 1835

VAN BUREN (now CASS) gained from JACKSON; VAN BUREN fully organized, detached from JACKSON. BATES attached to VAN BUREN "for all civil and military purposes." (Mo. Laws 1834-1835, priv. and loc., pp. 44-45)

14 March 1835

POLK gained from BARRY, GREENE, and ST. CLAIR. (Mo. Laws 1834-1835, priv. and loc., p. 44)

17 March 1835

Non-County Area 21 attached to PULASKI "for all civil and military purposes." (Mo. Laws 1834-1835, priv. and loc., p. 47)

19 March 1835

TANEY and WHITE (extinct) created from GREENE; TANEY and WHITE not fully organized, attached to GREENE "for all civil and military purposes." Non-County Area 22 gained from GREENE. (Mo. Laws 1843-1835, priv. and loc., p. 46)

16 December 1836

CLARK created from Non-County Area 19. (Mo. Laws 1836-1837, pub., pp. 47-48)

17 December 1836

AUDRAIN fully organized, detached from CALLAWAY, MONROE, and RALLS; AUDRAIN's boundaries defined [no change]. (Mo. Laws 1836-1837, pub., pp. 44-45)

29 December 1836

CALDWELL and DAVIESS created from Non-County Area 7; remainder of Non-County Area 7 detached from RAY and attached to DAVIESS "for civil and military purposes." (Mo. Laws 1836-1837, pub., pp. 46-47)

6 January 1837

LINN and Non-County Area 23 created from Non-County Area 6; Non-County Area 23 attached to LINN "for all civil and military purposes." Non-County Area 24 created from Non-County Area 6 and Non-County Area 19; Non-County Area 24 attached to MACON "for all civil and military purposes." (Mo. Laws 1836-1837, p. 52)

LIVINGSTON created from CHARITON, Non-County Area 6, and Non-County Area 18. Non-County Area 18 gained from Non-County Area 6; Non-County Area 18 detached from CARROLL and attached to LIVINGSTON "for all civil and military purposes." TANEY fully organized, detached from GREENE; TANEY's boundaries defined [no change]. Non-County Area 25 created from WHITE (extinct); Non-County Area 25 attached to TANEY "for all civil and military purposes". (Mo. Laws 1836-1837, pub., pp. 50-51)

MACON created from RALLS, Non-County Area 6, Non-County Area 10, and Non-County Area 19; Non-County Area 24 (created from Non-County Area 6) attached to MACON "for all civil and military purposes." Non-County Area 10 eliminated. (Mo. Laws 1836-1837, pub., p. 51)

14 January 1837

LINN gained from LIVINGSTON and Non-County Area 18. Non-County Area 23, attached to LINN, gained from Non-County Area 18. (Mo. Laws 1836-1837, pub., p. 53)

SHANNON created from CRAWFORD and RIPLEY; SHANNON attached to RIPLEY and WASHINGTON "for all civil and military purposes." (Mo. Laws 1836-1837, pub., pp. 54-55)

1 February 1837

GREENE boundaries defined [no change]. (Mo. Laws 1836-1837, pub., pp. 49-50)

6 February 1837

MILLER created from COLE, PULASKI, and Non-County Area 21; COLE gained from Non-County Area 21; Non-County Area 21 eliminated. (Mo. Laws 1836-1837, pub., pp. 53-54)

Non-County Area 26 and Non-County Area 27 created from Non-County Area 19. Non-County Area 26 attached to CLARK "for civil and military purposes." Non-County Area 27 attached to SHELBY "for civil and military purposes." (Mo. Laws 1836-1837, pub., pp. 48-49)

PULASKI gained from CRAWFORD. (Mo. Laws 1836-1837, pub., p. 54)

28 March 1837

The northwestern boundary of the State of Missouri was extended to the Missouri River, eliminating unorganized federal territory from Missouri. Non-County Area 28 created from unorganized federal territory, and attached to CLAY "for civil and military purposes." Non-County Area 12 gained from unorganized federal territory. (Mo. Laws 1836-1837, pub., p. 49; U.S. Stat., vol. 5, ch. 86[1836]/p. 34, and res. 2, p. 802)

15 December 1838

Missouri legislature extended CLARK's boundary line north of the commonly accepted boundary between Missouri and Iowa Territory (the Indian boundary line established in 1816); the extension overlapped Iowa's VAN BUREN, and created a dispute finally settled in Iowa's favor by the U.S. Supreme Court in 1849. Iowa maintained control of the area throughout the dispute. (Mo. Laws 1838-1839, pub., p. 22)

31 December 1838

BUCHANAN created from Non-County Area 12. PLATTE created from Non-County Area 12 and Non-County Area 28; Non-County Area 28 eliminated. (Mo. Laws 1838-1839, pub., pp. 23-25)

CLAY lost attached Non-County Area 28 to creation of PLATTE; Non-County Area 28 eliminated. (Mo. Laws 1838–1839, pub., pp. 23–25)

CLINTON lost part of attached Non-County Area 12 to creation of BUCHANAN and PLATTE. (Mo. Laws 1838–1839, pub., pp. 23–25)

NEWTON created from BARRY; Portion of BARRY and NEWTON overlapped until 28 March 1845. Non-County Area 29 created from BARRY, and attached to BARRY "for civil and military purposes." Non-County Area 30 created from BARRY, attached to NEWTON "for civil and military purposes." (Mo. Laws 1838-1839, pub., pp. 19-20)

Overlap area created between BARRY and NEWTON. (Mo. Laws 1838–1839, pub., pp. 19–20)

25 January 1839

RAY gained from Non-County Area 7. (Mo. Laws 1838-1839, pub., p. 25)

TANEY gained from Non-County Area 25. (Mo. Laws 1838-1839, pub., p. 27)

8 February 1839

MILLER boundaries defined [no change]. (Mo. Laws 1838-1839, pub., p. 23)

11 February 1839

Missouri expanded its claim to part of present Iowa by claiming a strip of land (approximately 10 miles wide) north of the present boundary, between the Des Moines and Missouri Rivers; the expansion implicitly extended the boundaries of the non-county areas attached to BUCHANAN, CLARK, CLINTON, DAVIESS, LEWIS, LINN, LIVINGSTON, and MACON, although there was no legislation relating the expansion directly to those counties [not mapped]. The encroachment overlapped Iowa's VAN BUREN and non-county area attached to VAN BUREN; Iowa continued to control the disputed area. (Mo. Laws 1838-1839, pub., p. 14)

Non-County Area 31 (Territory of Neatawah) created from Non-County Area 12, and attached to BUCHANAN "for civil and military purposes." (Mo. Laws 1838-1839, pub., pp. 21-22)

12 February 1839

GRUNDY created from Non-County Area 18; GRUNDY not fully organized, attached to LIVINGSTON "for all civil, judicial, and military purposes." (Mo. Laws 1838-1839, pub., p. 22)

Boundary between NEW MADRID and SCOTT defined [no change]. (Mo. Laws 1838-1839, pub., pp. 25-26)

11 January 1841

STODDARD gained from NEW MADRID. (Mo. Laws 1840-1841, pub., p. 44)

12 January 1841

Non-County Area 32 created from POLK, attached to POLK "for all civil and military purposes." (Mo. Laws 1848-1841, pub., pp. 42-43)

27 January 1841

Non-County Area 30 gained from NEWTON. (Mo. Laws 1840-1841, pub., p. 42)

29 January 1841

ADAIR created from Non-County Area 24. (Mo. Laws 1840-1841, pub., sec. 37/pp. 36-37)

ANDREW created from Non-County Area 31 (Territory of Neatawah). (Mo. Laws 1840-1841, pub., sec. 4/p. 33)

BATES gained from Non-County Area 30; BATES fully organized, detached from VAN BUREN (now CASS). (Mo. Laws 1840-1841, pub., secs. 34-36/p. 36)

DADE created from Non-County Area 29 and Non-County Area 32. (Mo. Laws 1840-1841, pub., sec. 10/pp. 33-34)

GRUNDY fully organized, detached from LIVINGSTON. (Mo. Laws 1840-1841, pub., sec. 13/p. 34)

JASPER created from Non-County Area 30. (Mo. Laws 1840-1841, pub., sec. 7/p. 33)

KINDERHOOK (now CAMDEN) created from MORGAN, PULASKI, and Non-County Area 16. (Mo. Laws 1840-1841, pub., sec. 28/pp. 35-36)

NIANGUA (now DALLAS) created from Non-County Area 32. (Mo. Laws 1840-1841, pub., sec. 16/p. 34)

NODAWAY (original) [now HOLT] created from Non-County Area 31 (Territory of Neatawah). (Mo. Laws 1840-1841, pub., sec. 1/pp. 32-33)

Non-County Areas 16, 19, 25, 26, 27, 29, 30, and 32 all eliminated. (Mo. Laws 1840-1841, pub., pp. 33-36)

OSAGE created from GASCONADE. (Mo. Laws 1840-1841, pub., sec. 40/p. 37)

OZARK created from RIPLEY, Non-County Area 22, and Non-County Area 25. (Mo. Laws 1840-1841, pub, sec. 22/p. 35)

SCOTLAND created from Non-County Area 19, Non-County Area 26, and Non-County Area 27. (Mo. Laws 1840-1841, pub., sec. 32/p. 36)

SHANNON fully organized, detached from RIPLEY and WASHINGTON; SHANNON boundaries defined [no change]. (Mo. Laws 1840-1841, pub., secs. 43-45/p. 37)

ST. CLAIR gained from Non-County Area 32; ST. CLAIR fully organized, detached from RIVES (now HENRY). (Mo. Laws 1840-1841, pub., secs, 25-27/p. 35)

WRIGHT created from PULASKI. (Mo. Laws 1840-1841, pub., sec. 19/p. 34)

2 February 1841

BATES gained from VAN BUREN (now CASS). (Mo. Laws 1840-1841, pub., p. 46)

11 February 1841

Non-County Area 33 created from WRIGHT, attached to WRIGHT "for civil and military purposes." (Mo. Laws 1840-1841, pub., pp. 46-47)

12 February 1841

GENTRY created from Non-County Area 12; GENTRY not fully organized, attached to CLINTON "for all civil and military purposes." (Mo. Laws 1840-1841, pub., p. 41)

Non-County Area 31 (Territory of Neatawah) detached from BUCHANAN, attached to ANDREW "for civil and military purposes." (Mo. Laws 1840-1841, pub., p. 40)

15 February 1841

RIVES renamed HENRY. (Mo. Laws 1840-1841, pub., pp. 40-41)

NODAWAY (original) renamed HOLT. (Mo. Laws 1840-1841, pub., p. 39)

Non-County Area 18 detached from LIVINGSTON, attached to GRUNDY "for civil and military purposes." (Mo. Laws 1840-1841, pub., p. 39)

Non-County Area 24 detached from MACON, attached to ADAIR "for all civil and military purposes." (Mo. Laws 1840-1841, pub., p. 40)

OREGON created from RIPLEY; OREGON not fully organized, attached to RIPLEY "for all civil and military purposes." (Mo. Laws 1840-1841, pub., p. 43)

19 December 1842

MISSISSIPPI created from SCOTT; MISSISSIPPI not fully organized, attached to SCOTT "for all civil, criminal, and military purposes." (Mo. Laws 1842-1843, pub., p. 42)

2 January 1843

NODAWAY created from Non-County Area 31 (Territory of Neatawah); NODAWAY not fully organized, attached to ANDREW "for civil and military purposes." Non-County Area 31 eliminated. (Mo. Laws 1842-1843, pub., p. 43)

STE. GENEVIEVE gained from ST. FRANCOIS. (Mo. Laws 1842-1843, pub., p. 45)

5 January 1843

DE KALB created from Non-County Area 12; DE KALB not fully organized, not attached. Non-County Area 12 eliminated. (Mo. Laws 1842-1843, pub., p. 36)

6 January 1843

KNOX created from SCOTLAND; KNOX not fully organized, attached to SCOTLAND "for civil and military purposes." (Mo. Laws 1842-1843, pub., pp. 46-47)

26 January 1843

LINCOLN exchanged with WARREN. (Mo. Laws 1842-1843, pub., pp. 30-40)

13 February 1843

SHELBY gained from MONROE. (Mo. Laws 1842-1843, pub., p. 47)

17 February 1843

ASHLEY (now TEXAS) created from SHANNON, WRIGHT, and Non-County Area 33; ASHLEY not fully organized, attached to SHANNON and WRIGHT "for all civil and military purposes." Non-County Area 33 eliminated. (Mo. Laws 1842-1843, pub., p. 35)

HIGHLAND (now SULLIVAN) created from part of Non-County Area 23; HIGHLAND (now SULLIVAN) not fully organized, attached to LINN "for all civil and military purposes." (Mo. Laws 1842-1843, pub., pp. 37-38)

Non-County Area 22 attached to WRIGHT "for all civil and military purposes." (Mo. Laws 1842-1843, pub., p. 48)

SCHUYLER created from Non-County Area 24; SCHUYLER not fully organized, attached to ADAIR "for all civil and military purposes." (Mo. Laws 1842-1843, pub., p. 46)

22 February 1843

OZARK renamed DECATUR; DECATUR boundaries defined [no change]. (Mo. Laws 1842-1843, pub., pp. 43-44)

HARRISON created from Non-County Area 7; HARRISON not fully organized, attached to DAVIESS "for civil and military purposes." Non-County Area 7 eliminated. (Mo. Laws 1842-1843, pub., p. 37)

MERCER created from Non-County Area 18; MERCER not fully organized, attached to GRUNDY "for civil and military purposes." Non-County Area 18 eliminated. (Mo. Laws 1842-1843, pub., p. 37)

PUTNAM created from Non-County Area 23 and Non-County Area 24; PUTNAM not fully organized, attached to ADAIR "for all civil and military purposes." Non-County Area 24 eliminated. (Mo. Laws 1842-1843, pub., pp. 44-45)

23 February 1843

KINDERHOOK renamed CAMDEN. (Mo. Laws 1842-1843, pub., p. 38)

CRAWFORD gained from PULASKI. (Mo. Laws 1842-1842, pub., p. 44)

24 February 1843

ALLEN (now ATCHISON) created from HOLT; ALLEN not fully organized, attached to HOLT "for all civil and military purposes." (History of Holt and Atchison Counties, 101, 285; Mo. Laws 1842-1843, pub., pp. 34-35)

AUDRAIN and MARION gained from MONROE. (Mo. Laws 1842-1843, pub., pp. 41-42)

LAWRENCE created from BARRY, DADE, and overlap area assigned to both BARRY and NEWTON. LAWRENCE not fully organized, parts attached to BARRY and DADE "for civil and military purposes." (Mo. Laws 1842-1843, pub., p. 39)

LINCOLN exchanged with WARREN. (Mo. Laws 1842-1843, pub., pp. 40-41)

25 February 1843

MADISON exchanged with SHANNON, and gained all of Non-County Area 14; Non-County Area 14 eliminated. (Mo. Laws 1842-1843, pub., p. 41)

27 February 1843

DUNKLIN created from STODDARD; DUNKLIN not fully organized, attached to STODDARD "for all civil, military, and judicial purposes." (Mo. Laws 1842-1843, pub., p. 36)

16 December 1844

NIANGUA renamed DALLAS. (Mo. Laws 1844-1845, loc. and priv., pp. 25-26)

14 February 1845

ALLEN renamed ATCHISON; ATCHISON fully organized, detached from HOLT; ATCHISON exchanged with HOLT. Overlap area created along ATCHISON's eastern border when NODAWAY's boundaries are redefined. (Mo. Laws 1844-1845, secs. 29-31/pp. 34-35)

CEDAR created from DADE and ST. CLAIR. (Mo. Laws 1844-1845, secs. 49-51/p. 37)

DUNKLIN fully organized, detached from STODDARD. (Mo. Laws 1844-1845, secs. 20, 48/pp. 33, 36)

GENTRY fully organized, detached from CLINTON; Non-County Area 34 created from GENTRY. (Mo. Laws 1844-1845, secs. 4-6/p. 31)

HARRISON fully organized, detached from DAVIESS. Non-County Area 35 created from HARRISON and attached to HARRISON "for all civil and military purposes." (Mo. Laws 1844-1845, secs. 10-11, 46/pp. 33, 46)

HICKORY created from BENTON and POLK. (Mo. Laws 1844-1845, secs. 16-18/pp. 32-33)

KNOX fully organized, detached from SCOTLAND. (Mo. Laws 1844-1845, secs. 26-28/p. 34)

LAWRENCE fully organized, detached from BARRY and DADE. (Mo. Laws 1844-1845, secs. 7-9/pp. 31-32)

MERCER fully organized, detached from GRUNDY. MISSISSIPPI fully organized, detached from SCOTT. (Mo. Laws 1844-1845, secs. 21, 41/pp. 33-34, 36)

MONITEAU created from COLE and MORGAN. (Mo. Laws 1844-1845, secs. 35-37/p. 35)

NODAWAY boundaries redefined; Overlap area created between NODAWAY and ATCHISON; NODAWAY fully organized, detached from ANDREW. (Mo. Laws 1844-1845, secs. 1-3/pp. 30-31)

OREGON fully organized, detached from RIPLEY. (Mo. Laws 1844-1845, secs. 35-37/p. 35)

HIGHLAND renamed SULLIVAN; SULLIVAN fully organized, detached from LINN. SCHUYLER fully organized, detached from ADAIR. (Mo. Laws 1844-1845, secs. 19, 43/pp. 33, 36)

ASHLEY renamed TEXAS; TEXAS fully organized, detached from SHANNON and WRIGHT. (Mo. Laws 1844-1845, secs. 12-14/p. 32)

25 February 1845

CAMDEN gained from MILLER. (Mo. Laws 1844-1845, loc. and priv., pp. 39-40)

DE KALB fully organized for administrative and judicial purposes. (Mo. Laws 1844-1845, loc. and priv., pp. 40-41)

REYNOLDS created from SHANNON and WAYNE; WAYNE gained from SHANNON. (Mo. Laws 1844-1845, loc. and priv., p. 41)

26 February 1845

PETTIS gained from BENTON. (Mo. Laws 1844-1845, loc. and priv., p. 42)

28 February 1845

Non-County Area 34 attached to GENTRY "for civil and military purposes." (Mo. Laws 1844-1845, loc. and priv., p. 44)

Non-County Area 36 created from PUTNAM; PUTNAM fully organized, detached from ADAIR. (Mo. Laws 1844-1845, loc. and priv., pp. 43-44)

15 March 1845

REYNOLDS exchanged with WAYNE. Non-County Area 23 detached from LINN and attached to SULLIVAN "for civil and military purposes." Non-County Area 36 attached to SULLIVAN "for civil and military purposes." (Mo. Laws 1844-1845, loc. and priv., p. 47)

17 March 1845

ST CLAIR gained from POLK. (Mo. Laws 1844-1845, loc. and priv., p. 47)

20 March 1845

LINN gained from CHARITON. SHANNON gained from TEXAS. (Mo. Laws 1844-1845, loc. and priv., p. 49)

24 March 1845

Non-County Area 37 created from WRIGHT, attached to WRIGHT "for all civil and military purposes." (Mo. Laws 1844-1845, loc. and priv., p. 50)

DECATUR renamed OZARK. (Mo. Laws 1844-1845, loc. and priv., pp. 51-52)

28 March 1845

BOONE gained from Non-County Area 3; Non-County Area 3 eliminated. (Mo. Rev. Stat. 1845, sec. 40/p. 138)

CRAWFORD gained from Non-County Area 11; Non-County Area 11 eliminated. (Mo. Rev. Stat. 1845, secs. 79, 84/pp. 144, 147)

MILLER gained from CAMDEN. (Mo. Rev. Stat. 1845, secs. 50, 91/pp. 140,146)

Overlap area between NODAWAY and ATCHISON assigned to NODAWAY. (Mo. Rev. Stat. 1845, secs. 71–72/pp. 143–144)

Overlap area between BARRY and NEWTON assigned to BARRY. (Mo. Rev. Stat. 1845, secs. 29–30/p.137)

SALINE gained from COOPER. (Mo. Rev. Stat. 1845, secs. 9, 69/pp. 134,143)

SCOTT gained from CAPE GIRARDEAU. (Mo. Rev. Stat. 1845, secs. 28, 84/pp. 137, 145-146)

WRIGHT gained from Non-County Area 22; Non-County Area 22 eliminated. (Mo. Rev. Stat. 1845, sec. 23/p. 136)

4 August 1846

Congress referred boundary dispute between Iowa and Missouri to United States Supreme Court for final determination. (U.S. Stat., vol. 9, ch. 82[1846]/pp. 52-53)

18 December 1846

DODGE (extinct) created from PUTNAM, Non-County Area 23, and Non-County Area 36; DODGE not fully organized, attached to PUTNAM "for all civil and military purposes." Non-County Area 23 and Non-County Area 36 eliminated. (Mo. Laws 1846-1847, pub., p. 16)

1 January 1847

SENECA (now McDONALD) created from NEWTON; SENECA not fully organized, attached to NEWTON "for all civil and military purposes." (Mo. Laws 1846-1847, pub., p. 16)

6 January 1847

Island in Missouri River (first island below Booneville) assigned to HOWARD [not mapped]. (Mo. Laws 1846-1847, priv., p. 229)

14 January 1847

NEWTON's eastern boundary defined [no change]. (Mo. Laws 1846-1847, priv., p. 230)

15 January 1847

DONALDSON (extinct) created from JACKSON, JOHNSON, LAFAYETTE, and VAN BUREN (now CASS); DONALDSON not fully organized, parts attached to JACKSON, JOHNSON, LAFAYETTE, and VAN BUREN "for all civil and military purposes." (Mo. Laws 1846-1847, pub., p. 17)

6 February 1847

Boundary between BATES and CEDAR defined [no change]. (Mo. Laws 1846-1847, pub., pp. 17-18)

15 February 1847

CAPE GIRARDEAU exchanged with PERRY. (Mo. Laws 1846-1847, pub., p. 18)

16 February 1847

JASPER gained from NEWTON. (Mo. Laws 1846-1847, priv., pp. 229-230)

10 December 1847

Boundary dispute between the states of Iowa and Missouri reached U.S. Supreme Court: dispute involved location of the rapids of the Des Moines River, from which point the boundary was to run due west. Missouri's interpretation put the boundary approximately 10 miles north of the present boundary (implicitly overlapping the Iowa counties of APPANOOSE, DAVIS, DECATUR, GREMONT, PAGE, RINGGOLD, TAYLOR, VAN BUREN, and WAYNE); Iowa argued for a line approximately 7 miles south of the present boundary (implicitly overlapping the Missouri counties of ATCHISON, CLARK, DODGE, HARRISON, MERCER, NODAWAY, PUTNAM, SCHUYLER, SCOTLAND, and non-county area attached to GENTRY and HARRISON). (Landers, 647; Thomas, 268-269)

24 January 1849

BARRY's western boundary defined [no change]. (Mo. Laws 1848-1849, pub., pp. 34-35)

5 February 1849

LINCOLN gained from MONTGOMERY. (Mo. Laws 1848-1849, pub., p. 34)

REYNOLDS gained from MADISON and WAYNE; WAYNE gained from MADISON. (Mo. Laws 1848-1849, pub., pp. 34-35)

13 February 1849

U.S. Supreme Court settled boundary dispute between Iowa and Missouri by rejecting both states' claims, choosing instead the Indian boundary line run and marked by John C. Sullivan in 1816 (the commonly accepted boundary before the dispute arose and the present boundary between the two states). The decision ended CLARK's overlap of the Iowa county of VAN BUREN. Also ended was Missouri's implicit overlap with the Iowa counties of APPANOOSE, DAVIS, DECATUR, FREMONT, PAGE, RINGGOLD, TAYLOR, VAN BUREN, and WAYNE, and Iowa's implicit overlap with the Missouri counties of ATCHISON, CLARK, DODGE (extinct), MERCER, NODAWAY, PUTNAM, SCHUYLER, SCOTLAND, and non-county areas attached to GENTRY and HARRISON. (Landers. 647-648; Thomas 269-270)

19 February 1849

VAN BUREN renamed CASS. (Mo. Laws 1848-1849, pub., pp. 20-30)

24 February 1849

LACLEDE created from CAMDEN, PULASKI, and Non-County Area 37. Non-County Area 37 eliminated. (Mo. Laws 1848-1849, pub., pp. 28-29)

27 February 1849

BUTLER created from WAYNE. (Mo. Laws 1848-1849, pub., pp. 25-27)

DODGE (extinct) fully organized, detached from PUTNAM. (Mo. Laws 1848-1849, pub., pp. 27-28)

DUNKLIN gained from NEW MADRID. (Mo. Laws 1848-1849, pub., p. 36)

2 March 1849

GREENE gained from TANEY. (Mo. Laws 1848-1849, pub., p. 36)

RIPLEY's boundaries defined [no change]. (Mo. Laws 1848-1849, pub., pp. 35-36)

3 March 1849

SENECA renamed McDONALD and fully organized, detached from NEWTON; McDONALD gained from NEWTON. (Mo. Laws 1848-1849, pub., pp. 30-32)

5 March 1849

CAPE GIRARDEAU exchanged with PERRY. (Mo. Laws 1848-1849, pub., p. 33)

7 March 1849

STE. GENEVIEVE gained from JEFFERSON. (Mo. Laws 1848-1849, pub., pp. 32-33)

8 March 1849

Creation of DONALDSON (extinct) repealed; parts reverted to CASS, JACKSON, JOHNSON, and LAFAYETTE; DONALDSON eliminated. (Mo. Laws 1848-1849, pub., p. 32)

10 March 1849

SCOTT gained from MISSISSIPPI. (Mo. Laws 1848-1849, pub., p. 33)

10 February 1851

DENT created from CRAWFORD and SHANNON. (Mo. Laws 1850-1851, pub., pp. 183-186)

MISSISSIPPI gained from SCOTT. (Mo. Laws 1850-1851, pub., p. 63)

STONE created from TANEY. (Mo. Laws 1850-1851, pub., pp. 186-188; Mo. Laws 1854-1855, pub., pp. 15-16)

19 February 1851

PEMISCOT created from NEW MADRID. (Mo. Laws 1850-1851, pub., pp. 190-192)

1 March 1851

BOLLINGER created from CAPE GIRARDEAU, STODDARD, and WAYNE. (Mo. Laws 1850-1851, pub., pp. 193-194)

HARRISON gained all of Non-County Area 35; Non-County Area 35 eliminated. (Mo. Laws 1850-1851, pub., p. 63)

4 August 1851

VERNON (original, extinct) created from BATES and CASS. (Atcheson, 133-134; History of Vernon Co., 192-193; Mo. Laws 1850-1851, pub., pp. 88-189; Mo. Reports 17: 521-529)

1 January 1853

Creation of VERNON (original, extinct) ruled unconstitutional by state supreme court; parts reverted to BATES and CASS. VERNON (original) eliminated. (Mo. Reports 17: 521-529)

18 February 1853

CAPE GIRARDEAU and DUNKLIN gained from STODDARD. (Mo. Laws 1852-1853, pub., p. 72; Mo. Laws 1856-1857, loc., pp. 329-330)

16 March 1853

PUTNAM gained all of DODGE (extinct); DODGE eliminated. (Mo. Laws 1852-1853, pub., pp. 72-74)

10 January 1855

LIVINGSTON gained from LINN. (Mo. Laws 1854-1855, pub., p. 17)

22 February 1855

BATES gained from CASS. (Mo. Laws 1854-1855, pub., pp. 11-12)

27 February 1855

VERNON created from BATES. (Mo. Laws 1854-1855, pub., pp. 17-18)

28 February 1855

GREENE gained from OZARK and WRIGHT; TANEY gained from GREENE. (Mo. Laws 1854-1855, pub., p. 15)

1 March 1855

OSAGE gained from PULASKI. (Mo. Laws 1854-1855, pub., p. 12)

2 March 1855

MARIES created from OSAGE. (Mo. Laws 1854-1855, pub., pp. 13-15)

3 March 1855

WEBSTER created from GREENE. (Mo. Laws 1854-1855, pub., p. 16)

1 December 1855

CRAWFORD gained all of DENT; DENT eliminated. (Mo. Laws 1855, adj. sess., loc. and priv., pp. 34-35)

4 December 1855

BATES's southern boundary defined [no change]. (Mo. Laws 1855, adj. sess., loc. and priv., pp. 36-37)

COLE gained from OSAGE. (Mo. Laws 1855, adj. sess., loc. and priv., p. 32)

DENT re-created from CRAWFORD. (Mo. Laws 1855, adj. sess., loc. and priv., pp. 37-38)

5 December 1855

DENT gained from TEXAS. (Mo. Laws 1855, adj. sess., loc. and priv., pp. 44-45)

7 December 1855

WEBSTER gained from DALLAS and GREENE. OZARK boundaries defined [no change]. WRIGHT boundaries defined [no change]. (Mo. Laws 1855, adj. sess., loc. and priv., pp. 40-42)

12 December 1855

BARTON created from JASPER. (Mo. Laws 1855, adj. sess., loc. and priv., pp. 49-50)

13 December 1855

CAMDEN boundaries redefined, creating an overlap with MILLER. (Mo. Laws Rev., 1854-1855, ch. 41, secs. 49,75 /pp. 471-472, 483)

DENT gained from SHANNON. (Mo. Laws Rev., 1854-1855, ch. 41, secs. 58, 93/pp. 476-477, 490)

STODDARD gained from NEW MADRID; STODDARD boundary with DUNKLIN incorrectly defined as that existing prior to 18 February 1853; definition corrected on 4 March 1857 [no change]. (Mo. Laws Rev., 1854-1855, ch. 41, secs. 59, 79, 94/pp. 477, 484-485, 490-491)

15 January 1857

BOLLINGER's boundaries defined [no change]. (Mo. Laws 1856-1857, loc., pp. 237-238)

30 January 1857

Boundaries between MISSISSIPPI and SCOTT and between MISSISSIPPI and NEW MADRID defined [no change]. (Mo. Laws 1856-1857, loc., pp. 273, 439-440)

17 February 1857

IRON created from MADISON, REYNOLDS, ST. FRANCOIS, WASHINGTON, and WAYNE. ST. FRANCOIS gained from WASHINGTON. (Mo. Laws 1856-1857, gen., pp. 52-55)

2 March 1857

HOWELL created from OREGON. (Mo. Laws 1856-1857, gen., pp. 51-52)

3 March 1857

IRON gained from CRAWFORD, DENT, and WASHINGTON. (Mo. Laws 1856-1857, gen., p. 55)

4 March 1857

DUNKLIN / STODDARD boundary change of 18 February 1853 "revived and reenacted" (repealing DUNKLIN's boundary description in Revised Statutes, enacted 13 December 1855) [no change]. (Mo. Laws 1856-1857, loc., pp. 329-330)

29 October 1857

DOUGLAS created from OZARK. (Mo. Laws 1857, adj. sess., loc., pp. 288-289)

4 November 1857

CRAWFORD gained from IRON and PULASKI. (Mo. Laws 1857, adj. sess., loc., pp. 406-407)

5 November 1857

NODAWAY gained from ATCHISON. (Mo. Laws 1857, adj. sess., loc., pp. 386-387)

13 November 1857

PHELPS created from CRAWFORD and MARIES. (Mo. Laws 1857, adj. sess., loc., pp. 397-398)

4 March 1859

MARIES exchanged with PHELPS. (Mo. Laws 1858-1859, pp. 371-372)

8 March 1859

CHRISTIAN created from GREENE, TANEY, and WEBSTER. (Mo. Laws 1858-1859, pp. 321-323)

10 March 1859

CARTER created from RIPLEY and SHANNON; SHANNON gained from RIPLEY. (Mo. Laws 1858-1859, pp. 314-316)

Boundary between JEFFERSON and STE. GENEVIEVE defined [no discernible change]. (Mo. Laws 1858-1859, p. 361)

MISSISSIPPI exchanged with SCOTT. (Mo. Laws 1858-1859, p. 411)

12 March 1859

PHELPS gained from PULASKI. (Mo. Laws 1858-1859, p. 393)

SHANNON gained from OREGON. (Mo. Laws 1858-1859, p. 413)

ST. CLAIR gained from HENRY. (Mo. Laws 1858-1859, p. 425)

14 March 1859

BOLLINGER gained from STODDARD. (Mo. Laws 1858-1859, p. 304; Vernon's Annotated Missouri Statutes 1949, 4:15)

HOLT boundaries defined [no discernible change]. (Mo. Laws 1858-1859, p. 349)

31 December 1859

WEBSTER boundaries defined [no change]. (Mo. Laws 1859-1860, adj. sess., p. 536)

14 January 1860

DENT gained from TEXAS. (Mo. Laws 1859-1860, adj. sess., p. 474)

16 January 1860

ATCHISON gained from NODAWAY. (Mo. Laws 1859-1860, adj. sess., p. 464)

MILLER gained from MORGAN. (Mo. Laws 1859-1860, adj. sess., p. 495)

25 January 1861

NODAWAY gained from ATCHISON. (Mo. Laws 1860-1861, loc., p. 382)

25 February 1861

WORTH created from Non-County Area 34; Non-County Area 34 eliminated. (Mo. Laws 1860-1861, loc., pp. 470-473)

25 February 1863

WORTH gained from NODAWAY. (Mo. Laws 1862-1863, p. 57; Mo. Laws 1870, adj. sess., pp. 193-194)

18 March 1863

RIPLEY gained from BUTLER. (Mo. Laws 1862-1863, loc., p. 56)

12 December 1863

GENTRY's boundary defined [no change]. (Mo. Laws 1863-1864, adj. sess., spec., pp. 408-409)

21 January 1864

BUTLER gained from RIPLEY. (Mo. Laws 1863-1864, adj. sess., spec., p. 409)

5 February 1864

DOUGLAS gained from WEBSTER. (Mo. Laws 1863-1864, adj. sess., spec., p. 280)

20 November 1864

DOUGLAS gained from TANEY. (Mo. Laws 1863-1864, adj. sess., spec., p. 280)

10 February 1865

CAPE GIRARDEAU exchanged with SCOTT. (Mo. Laws 1864-1865, adj. sess., spec., pp. 310-311)

27 February 1868

PHELPS gained from MARIES. (Mo. Laws 1868, adj. sess., gen., pp. 23-24)

24 March 1868

Missouri Legislature passed a single law adjusting the boundaries of 16 counties and one overlap area. (Mo. Laws 1868, adj. sess., gen., pp. 16-23)

25 March 1868

DENT gained from REYNOLDS; REYNOLDS gained from IRON and SHANNON. (Mo. Laws 1868, adj. sess., gen., pp. 24-25)

3 March 1869

CRAWFORD gained from GASCONADE and IRON. (Mo. Laws 1869, gen., pp. 9-10)

11 January 1870

JEFFERSON's and STE. GENEVIEVE's boundaries defined [no discernible change]. (Mo. Laws 1870, adj. sess., gen., pp. 32-33)

8 February 1870

TEXAS gained from DOUGLAS. (Mo. Laws 1870, adj. sess., gen., pp. 33-34)

17 March 1870

BARRY's boundaries defined [no change]. (Mo. Laws 1870, adj. sess., gen., p. 34)

11 January 1872

DOUGLAS gained from TEXAS. (Mo. Laws 1871-1872, adj. sess., gen., pp. 22-23)

9 March 1872

Missouri Legislature passed a single law adjusting the boundaries of 8 counties. (Mo. Laws 1871-1872, adj. sess., gen., pp. 25-26)

14 March 1872

SCOTT's boundaries defined [no change]. STODDARD exchanged with NEW MADRID and WAYNE. (Mo. Laws 1871-1872, adj. sess., gen., pp. 23-24)

1 April 1872

BUTLER exchanged with RIPLEY. (Mo. Laws 1871-1872, adj. sess., gen., pp. 21-22; Mo. Laws 1874, adj. sess., gen., p. 28)

23 March 1874

DUNKLIN's boundaries defined [no change]. (Mo. Laws 1874, adj. sess., gen., p. 29)

20 March 1875

ST. FRANCOIS's boundaries defined [no change]. (Mo. Laws 1875, gen., pp. 32-33)

29 March 1875

CAMDEN exchanged with MILLER. (Mo. Laws 1875, gen., pp. 30-31)

22 October 1876

ST. LOUIS CITY created from ST. LOUIS county. (Hyde and Conard, 4: 1993-1996)

31 May 1879

COLE gained from MILLER. HOWELL gained from OZARK. IRON gained from CRAWFORD (the area gained by IRON was incorrectly included as part of CRAWFORD in the state's Revised Statutes until 1929). McDONALD gained from NEWTON. (Mo. Rev. Stat. 1879, pp. 1015-1044)

ST. CLAIR gained from BENTON (the area gained by ST. CLAIR was incorrectly included as part of BENTON in the state's Revised Statutes until 1939). (Mo. Laws 1889, p. 66; Mo. Laws 1939, pp. 635-636, 653-654; Mo. Vernon's 1949, pp. 13-14)

17 March 1881

MORGAN's boundaries clarified [no change]. (Mo. Laws 1881, p. 94)

24 March 1881

MARIES's boundaries clarified [no change]. (Mo. Laws 1881, p. 93)

27 March 1883

Boundaries of BUTLER, STODDARD, and WAYNE clarified [no change]. (Mo. Laws 1883, pp. 55-57)

17 May 1899

PULASKI's boundaries clarified [no change]. (Mo. Laws 1899, pp. 145-146)

3 August 1950

Missouri and Kansas exchanged territory along the Missouri River from 40 degrees north latitude to the Kansas River. The change was made to accommodate shifts in the course of the Missouri River following the 1944 flood. It took effect on 3 August 1950 after the United States Congress approved a joint resolution establishing the permanent boundary between the two states [not mapped]. (U.S. Stat., vol. 64, ch. 519 [1950]/p. 397; Mo. Laws 1949, S.B. 141, p. 311; Kans. Laws 1949, 53d leg., chs. 196, 510/pp. 293-294, 837-838)