New Mexico Atlas of Historical County Boundaries
John H. Long, Editor; Peggy Tuck Sinko, Associate Editor; Emily Kelley, Historical Compiler; 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 River to the Rocky Mountains). (Parry, 57:27-40; Van Zandt, 23-26)
01 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); New Madrid District (now NEW MADRID, Mo.) created within the District of Louisiana (Mo.); included the northeast corner of present New Mexico. (Terr. Papers U.S., 13: 51-52; U.S. Stat., vol. 2, ch. 38 [1804]/pp. 283-289; Violette, 46-47)
01 July 1806
New Madrid District (now NEW MADRID, Mo.) gained from Cape Girardeau District (now CAPE GIRARDEAU, Mo.); portion of New Madrid in present New Mexico unchanged. (Terr. Papers U.S., 13:541-542; Gov. Proc. 7 June 1806)
15 August 1806
Cape Girardeau District (now CAPE GIRARDEAU, Mo.) gained from New Madrid District (now NEW MADRID, Mo.); included part of the northeast corner of present New Mexico. (Ford, 5-6)
07 December 1812
Non-county area in Missouri Territory created from CAPE GIRARDEAU (Mo.), NEW MADRID (Mo.), ST. LOUIS (Mo.), and STE. GENEVIEVE (Mo.), when their western boundaries were redefined as the boundary of the "Osage Purchase". Non-county are overlapped the northeast corner of present New Mexico; only the area of overlap is mapped. (Royce, 676-677, pls. 112, 144; Terr. Papers U.S., 14:599-601)
31 December 1813
Non-county area in Missouri Territory lost to creation of ARKANSAS (Ark.); portion of non-county area that overlapped present New Mexico unchanged. (Mo. Terr. Laws 1813-1814, ch. 99, sec. 1/pp. 293-295)
22 February 1819
All of present New Mexico came under Spanish control when the Adams-Onis Treaty between the United States and Spain established the boundary between the two countries from the Gulf of Mexico to the Pacific Ocean. Ratifications exchanged 22 February 1821. (Parry, 70:1-30; Van Zandt, 26-27)
24 August 1821
Mexico gained its independence from Spain; present New Mexico became part of the Republic of Mexico. (Beers, 100; "Mexican War of Independence," New Handbook of Texas, 4:698)
06 July 1824
New Mexico was declared a territory of the Republic of Mexico; included western part of present Texas. (Stribling, 16; Weber, 23-25)
12 January 1828
Treaty of Limits between Mexico and the United States defined the boundary between the two countries to be the same as established by the 1819 Adams-Onis Treaty with Spain. (Parry, 78:35-42; Van Zandt, 121)
19 December 1836
The Republic of Texas officially established its boundaries: on the north and east, the Adams-Onis Treaty line; on the south the Rio Grande River; and on the west, from the source of the Rio Grande River north to the 42d parallel; BEXAR (Tex.) boundaries expanded to include all territory claimed in the new definition; included the entire eastern half of present New Mexico, and parts of present Colorado and Wyoming. Territory claimed by Texas was officially a part of Mexico and remained in dispute, though neither the Republic of Texas nor Mexico established effective control of the area. Only the portion of Texas in present New Mexico is mapped. (Texas Repub. Laws 1836, 1st cong./p. 133; Donnell, 69; Frantz and Cox, 29, 31; Stephens and Holmes, 34)
29 December 1836
New Mexico became a Department in the Republic of Mexico when the new Constitution became law. (Bloom, 3-18)
29 December 1845
Congress admitted the state of Texas to the Union; Republic of Texas eliminated. Between 19 December 1836 and 13 December 1850 Texas continued to promote its claim to the eastern half of present New Mexico by creating the counties of BEXAR (Tex.), EL PASO (Tex.), SANTA FE (Tex.), and WORTH (Tex., extinct). Competing claims to eastern New Mexico resulted in overlaps between the Texas counties and the New Mexico counties created by Gen. Kearny in 1846. For clarity map shows only a simplified version of the multiple county overlaps. (U.S. Stat., vol. 9, res. 1 [1845]/p. 108; Van Zandt, 122)
13 May 1846
Following a series of boundary skirmishes, and repeated attempts by Texas to claim all that portion of Mexico located between the Nueces River and the Rio Grande River, Congress declared a state of war between the United States and Mexico. (U.S. Stat., vol. 9, ch. 16[1846]/pp. 9-10; Williams 108-110)
18 August 1846
The U.S. Army of the West, under command of Brigadier General Stephen Watts Kearny, took control of Santa Fe and proclaimed United States sovereignty over the territory of New Mexico (Mexico). (Williams 108-110)
22 September 1846
Kearny's Code of Laws was promulgated in Santa Fe for use in the occupied Mexican territory. Code included a Bill of Rights, Laws for the Government of the Territory of New Mexico, and established civil and judicial appointments for the seven original counties of: BERNALILLO, RIO ARRIBA, SAN MIGUEL, SANTA FE, SANTA ANA, TAOS, and VALENCIA. Mexico effectively lost control over the area; State of Texas continued to claim its boundary extended as far west as the Rio Grande River resulting in an overlap between BEXAR (Tex.) and all seven Kearny counties. (Kearny's Code 1846, "Courts and Judicial Powers, secs. 5-7/p. 49; Abel, Map #2; Coan, 252; Williams, 108-109)
04 July 1848
Treaty of Guadalupe-Hidalgo ended the war between Mexico and the United States. Area ceded by Mexico became Unorganized Federal Territory (non-county area) in the United States; included all of present California, Nevada, and Utah, and parts of present Arizona, Colorado, New Mexico, and Wyoming. Texas claimed the portion of Unorganized Federal Territory located east of the Rio Grand River as part of BEXAR (Tex.); Mexico retained parts of present Arizona and New Mexico and part of the international boundary was in dispute. (U.S. Stat., vol. 9, pp. 922-943; Parry, 102: 29-59; Van Zandt, 11, 28-29; Walker and Bufkin, 19, 20A)
31 December 1848
General Assembly of the Territory of New Mexico convened in December 1847, prior to formal designation of New Mexico Territory by the United States Congress. Law approved December 1848 established Circuit Court districts for the territory, thereby officially recognizing the counties of BERNALILLO, RIO ARRIBA, SAN MIGUEL, SANTA ANA (extinct), SANTA FE, TAOS, and VALENCIA as established by the Kearny Code of 22 September 1846.
13 December 1850
The United States created New Mexico Territory from Unorganized Federal Territory (land ceded by Mexico to the United States in the Treaty of Guadalupe-Hidalgo) and from territory purchased from the state of Texas; included most of present Arizona and New Mexico, and parts of present Colorado and Nevada. Faulty geographic information on the Disturnell map referenced in the treaty led to a dispute between the United States and Mexico over the exact location and extent of the international boundary. All that portion of New Mexico Territory lying outside the boundaries of the seven original counties established under Kearny's Code became Non-County Area 1; included most of present Arizona and New Mexico, and parts of present Colorado and Nevada. Texas eliminated from New Mexico. The portion of Arizona south of the Gila River was part of Mexico. (U.S. Stat., vol. 9, ch. 49[1850]/pp. 446-452; Baldwin, 117-137; Coffey, 145-164; Van Zandt, 28-29, 162-165)
09 January 1852
Legislature passed a single act creating two new counties, redefining boundaries for the seven original counties to extend across the limits of the territory, and eliminating all of Non-County Area 1. (N.M. Terr. Laws 1851, 1st assy., 1st sess./p. 119; N.M. Terr. Laws 1851, 1st assy., 2d sess. /pp. 266, 291-292; for pages on particular counties, see following citations)
DOŅA ANA created by New Mexico Territory from Non-County Area 1; included parts of present Arizona and New Mexico, and the disputed area with Mexico. DOŅA ANA first mentioned in a 10 July 1851 law establishing judicial districts, and on 06 January 1852 the legislature authorized its creation from SOCORRO, however, no complete boundary definition is given for either county until 09 January 1852. (pp. 119, 266, 292)
SOCORRO created by New Mexico Territory from Non-County Area 1; included parts of present Arizona and New Mexico. SOCORRO first mentioned in a 10 July 1851 establishing judicial districts, and on 06 January 1852 legislature authorized creation of DOŅA ANA from SOCORRO, however, no complete boundary definition is given for either county until 09 January 1852. (pp. 119, 266, 292)
BERNALILLO gained from VALENCIA and Non-County Area 1, exchanged with SAN MIGUEL, and lost to SANTA ANA and SANTA FE when all counties redefined; included parts of present Arizona, Nevada and New Mexico. (p. 292)
RIO ARRIBA gained from SAN MIGUEL, SANTA ANA, SANTA FE and Non-County Area 1, and exchanged with TAOS when all counties redefined; included parts of present Arizona, Nevada and New Mexico. (p. 291)
SAN MIGUEL gained from SANTA FE and Non-County Area 1, and exchanged with BERNALILLO and TAOS when all counties redefined. (p. 291)
SANTA ANA (extinct) gained from BERNALILLO and Non-County Area 1, exchanged with SANTA FE, and lost to RIO ARRIBA when all counties redefined; included parts of present Arizona, Nevada, and New Mexico. (p. 292)
SANTA FE gained from BERNALILLO, exchanged with SANTA ANA, and lost to RIO ARRIBA and SAN MIGUEL when all counties redefined. (p. 291)
TAOS gained from Non-County Area 1, and exchanged with RIO ARRIBA and SAN MIGUEL when all counties redefined; included parts of present Arizona, Colorado, Nevada and New Mexico. (p. 291)
VALENCIA gained from Non-County Area 1, lost to creation of SOCORRO, and lost to BERNALILLO when all counties redefined; included parts of present Arizona, Nevada, and New Mexico. (p. 292)
30 December 1853
Gadsden Purchase settled the boundary dispute between the United States and Mexico and established the international line at its present location. (U.S. Stat., vol. 10, pp. 1031-1037; Van Zandt, 11, 29, 162)
04 August 1854
Non-County Area 2 created when the territory acquired by the United States in the Gadsden Purchase was officially added to New Mexico Territory without being assigned to a county. (U.S. Stat., vol. 10, ch. 245[1854]/p. 575; Van Zandt, 162; Walker and Bufkin, 21-22)
03 February 1855
DOŅA ANA gained all of Non-County Area 2. (N.M. Terr. Laws 1854, 4th assy. /p. 57)
01 February 1860
ARIZONA (extinct) created by New Mexico Territory from DOŅA ANA. ARIZONA (extinct) was located entirely within present Arizona. (N.M. Terr. Laws 1859-1860, 9th assy. /p. 74)
MORA created by New Mexico Territory from TAOS; included parts of present Colorado and New Mexico. (N.M. Terr. Laws 1859-1860, 9th assy. /p. 76)
05 April 1860
An unofficial convention held in Tucson (Ariz.) established a provisional government, declared the creation of the Territory of Arizona from all that part of New Mexico Territory that lay south of 33 degrees 40 minutes north latitude, and authorized the creation of four counties: CASTLE DOME (Ariz., proposed), DOŅA ANA (Ariz., proposed), EWELL (Ariz., proposed), and MESILLA (Ariz., proposed). United States Congress failed to recognize the new territory and its proposed counties [no change]. (Sacks, 36, 151; Swindler, 1:244-248)
12 January 1861
SAN JUAN (original, extinct) created by New Mexico Territory from TAOS; included parts of present Arizona, New Mexico, and Nevada. (N.M. Terr. Laws 1860-1861, 10th assy. /p. 16)
28 February 1861
The United States created Colorado Territory from New Mexico, Utah, Kansas, and Nebraska Territories; TAOS and MORA lost to Colorado Territory. (U.S. Stat., vol. 12, pp. 172-177; Van Zandt, 141-144)
18 January 1862
DOŅA ANA gained all of ARIZONA (extinct) when the law creating ARIZONA was repealed. (N.M. Terr. Laws 1861-1862, 11th assy. /p. 18)
TAOS gained all of SAN JUAN (original, extinct) when the law creating SAN JUAN was repealed. (N.M. Terr. Laws 1861-1862, 11th assy. /p. 16)
28 January 1863
ARIZONA (extinct) re-created from DOŅA ANA. (N.M. Terr. Laws 1862-1863, 12th assy. /p.30)
24 February 1863
The United States created Arizona Territory from New Mexico Territory. ARIZONA (extinct) eliminated; BERNALILLO, DOŅA ANA, RIO ARRIBA, SANTA ANA (extinct), SOCORRO, TAOS, and VALENCIA all lost to Arizona Territory. (U.S. Stat., vol. 12, pp. 664-665; Van Zandt, 165)
03 February 1864
SANTA FE gained from SAN MIGUEL. (N.M. Terr. Laws 1863-1864, 13th assy. /p. 88)
31 January 1867
SOCORRO gained from DOŅA ANA. (N.M. Terr. Laws 1866-1867, 16th assy. /p. 104)
30 January 1868
GRANT created by New Mexico Territory from DOŅA ANA and SOCORRO. (N.M. Terr. Laws 1867-1868, 17th assy., ch. 20/p. 88)
Boundary between MORA and TAOS redefined [no change]. (N.M. Terr. Laws 1867-1868, 17th assy., ch. 24/p. 106)
by 15 January 1869
SAN MIGUEL had gained from BERNALILLO, SOCORRO, and VALENCIA. Though no law has been found authorizing this change, the definition for the creation of LINCOLN on 16 January 1869 depends on the SAN MIGUEL boundary having been extended southward as mapped. (Coan, 259)
16 January 1869
LINCOLN created by New Mexico Territory from SOCORRO. (N.M. Terr. Laws 1868-1869, 18th assy., ch. 8/pp. 28-31)
18 January 1869
SANTA FE gained from RIO ARRIBA [law repealed 1 January 1871]. (N.M. Terr. Laws 1868-1869, 18th assy., ch. 11/pp. 36-38)
25 January 1869
COLFAX created by New Mexico Territory from MORA. (N.M. Terr. Laws 1868-1869, 18th assy., ch. 24/pp. 57-62)
10 January 1870
DOŅA ANA gained from SOCORRO. (N.M. Terr. Laws 1869-1870, 19th assy., ch. 11/p. 36)
13 January 1870
VALENCIA gained from BERNALILLO. (N.M. Terr. Laws 1869-1870, 19th assy., ch. 16/p. 44)
01 January 1871
RIO ARRIBA gained from SANTA FE when the law of 18 January 1869 was repealed. (N.M. Terr. Laws 1869-1870, 19th assy., ch. 13/p.40)
29 December 1871
SOCORRO gained from DOŅA ANA. (N.M. Terr. Laws 1871-1872, 20th assy., ch. 2/pp. 4-5)
13 January 1876
BERNALILLO gained all of SANTA ANA (extinct); SANTA ANA eliminated. (N.M. Terr. Laws 1875-1876, 22d assy., ch. 8/pp. 38-40)
COLFAX gained from MORA. (N.M. Terr. Laws 1875-1876, 22d assy., ch. 61/p. 162)
14 January 1876
COLFAX attached to TAOS "for judicial purposes" [law repealed 24 January 1878]. (N.M. Terr. Laws 1875-1876, 22d assy., ch.6/pp. 35-37)
24 January 1878
COLFAX detached from TAOS when the law of 14 January 1876 was repealed. (N.M. Terr. Laws 1878, 23d assy., ch. 9/p. 60)
15 February 1878
LINCOLN gained from DOŅA ANA. (N.M. Terr. Laws 1878, 23d assy., ch. 34/pp. 82-83)
10 February 1880
RIO ARRIBA exchanged with TAOS. (N.M. Terr. Laws 1880, 24th assy., ch. 46/pp. 103-104)
11 February 1880
SOCORRO gained from DOŅA ANA. (N.M. Terr. Laws 1880, 24th assy., ch. 42/pp. 98-99)
13 February 1880
DOŅA ANA gained from GRANT. (N.M. Terr. Laws 1880, 24th assy., ch. 43/p. 99)
17 January 1882
MORA gained from SAN MIGUEL. (N.M. Terr. Laws 1882, 25th assy., ch. 86/pp. 176-177)
31 January 1882
MORA gained from COLFAX. (N.M. Terr. Laws 1882, 25th assy., ch. 72/pp. 158-159)
04 March 1882
SANTA FE gained from MORA, exchanged with BERNALILLO and SAN MIGUEL. BERNALILLO was divided into two parts encompassing territory east and west of SANTA FE. (N.M. Terr. Laws 1882, 25th assy., ch. 83/p. 174)
03 April 1884
SIERRA created by New Mexico Territory from DOŅA ANA, GRANT, and SOCORRO. Creation left a small portion of SOCORRO to the south of SIERRA. (N.M. Terr. Laws 1884, 26th assy, ch. 109/pp. 223-225)
24 February 1887
DOŅA ANA gained from LINCOLN and SOCORRO. (N.M. Terr. Laws 1887, 27th assy., ch. 14/p. 39)
SAN JUAN created by New Mexico Territory from RIO ARRIBA. (N.M. Terr. Laws 1887, 27th assy., ch. 13/p. 38)
12 February 1889
LINCOLN gained from DOŅA ANA. (N.M. Terr. Laws 1888, 28th assy., ch. 41/pp. 92-93)
Boundary between MORA and SAN MIGUEL redefined [no change]. (N.M. Terr. Laws 1888, 28th assy., ch. 37/p. 89)
28 February 1889
SANTA FE gained from RIO ARRIBA, exchanged with BERNALILLO, lost to MORA and SAN MIGUEL. (N.M. Terr. Laws 1888, 28th assy., ch. 127/pp. 301-302)
01 January 1891
CHAVES and EDDY created by New Mexico Territory from LINCOLN. EDDY not fully organized, attached to CHAVES "for judicial purposes." (N.M. Terr. Laws 1888, 28th assy., ch. 87/pp. 202-207)
25 February 1891
BERNALILLO gained from SANTA FE. (N.M. Terr. Laws 1891, 29th assy., ch. 55/pp. 106-107)
16 May 1891
EDDY fully organized; detached from CHAVES. (N.M. Terr. Laws 1891, 29th assy., ch. 19/p. 38)
01 January 1893
GUADALUPE (original) created by New Mexico Territory from SAN MIGUEL. (N.M. Terr. Laws 1891, 29th assy., ch. 88/pp. 175-180)
13 February 1893
VALENCIA gained from LINCOLN; SOCORRO boundary with LINCOLN redefined [no change]. (N.M. Terr. Laws 1893, 30th assy., ch. 20/pp. 36-37)
01 January 1894
UNION created by New Mexico Territory from COLFAX, MORA, and SAN MIGUEL. (N.M. Terr. Laws 1893, 30th assy., ch. 49/pp. 68-75)
16 January 1895
EDDY gained from LINCOLN. (N.M. Terr. Laws 1895, 31st assy., ch. 11/p. 42)
28 February 1895
BERNALILLO gained from RIO ARRIBA. (N.M. Terr. Laws 1895, 31st assy., ch. 10/pp. 41-42)
UNION boundary was clarified to correct an "uncertainty, ambiguity and apparent contradiction in the language" of the 1 January 1894 law [no change]. (N.M. Terr. Laws 1895, 31st assy., ch. 12/p. 43)
13 February 1897
GUADALUPE (original) gained from BERNALILLO. (N.M. Terr. Laws 1897, 32d assy., ch. 8/p. 22)
30 January 1899
OTERO created by New Mexico Territory from DOŅA ANA, LINCOLN, and SOCORRO; CHAVES gained from LINCOLN. (N.M. Terr. Laws 1899, 33d assy., ch. 3/pp. 21-30)
01 January 1901
McKINLEY created by New Mexico Territory from BERNALILLO; VALENCIA gained from BERNALILLO. (N.M. Terr. Laws 1899, 33d assy., ch. 19/pp. 43-45)
16 March 1901
LUNA created by New Mexico Territory from DOŅA ANA and GRANT. (N.M. Terr. Laws 1901, 34th assy., ch. 38/pp. 70-75)
18 March 1901
McKINLEY gained from BERNALILLO, SAN JUAN, and VALENCIA; VALENCIA gained from BERNALILLO. (N.M. Terr. Laws 1901, 34th assy., ch. 39/pp. 75-79)
28 February 1903
QUAY created by New Mexico Territory from GUADALUPE (original) and UNION. (N.M. Terr. Laws 1903, 35th assy., ch. 8/pp. 16-20)
ROOSEVELT created by New Mexico Territory from CHAVES and GUADALUPE (original). (N.M. Terr. Laws 1903, 35th assy., ch. 7/pp. 12-16)
10 March 1903
RIO ARRIBA gained from SANTA FE. (N.M. Terr. Laws 1903, 35th assy., ch. 24/p. 35)
16 March 1903
LEONARD WOOD (now GUADALUPE) created by New Mexico Territory from GUADALUPE (original) and VALENCIA; Non-County Area 3 created from a remnant of GUADALUPE (original), which was eliminated. (N.M. Terr. Laws 1903, 35th assy., ch. 69/pp. 127-131)
14 April 1903
SANDOVAL created by New Mexico Territory from BERNALILLO. (N.M. Terr. Laws 1903, 35th assy., ch. 27/pp. 37-43)
01 January 1905
TORRANCE created by New Mexico Territory from BERNALILLO, LINCOLN, SAN MIGUEL, SANTA FE, SOCORRO, and VALENCIA. (N.M. Terr. Laws 1903, 35th assy., ch. 70/pp. 132-134)
02 February 1905
TORRANCE gained from SAN MIGUEL, SOCORRO, and VALENCIA. (N.M. Terr. Laws 1905, 36th assy., ch. 2/pp. 2-3)
20 February 1905
TAOS gained small area [near Tres Piedras] from RIO ARRIBA. (N.M. Terr. Laws 1905, 36th assy., ch. 11/pp. 39-40)
23 February 1905
LEONARD WOOD renamed GUADALUPE. (N.M. Terr. Laws 1905, 36th assy., ch. 20/p. 57)
08 May 1905
RIO ARRIBA and SANTA FE gained from SANDOVAL when SANDOVAL was abolished, then immediately re-created on the same day with slightly different boundaries. (N.M. Terr. Laws 1905, 36th assy., ch. 10/pp. 34-39)
20 March 1907
QUAY gained from SAN MIGUEL and UNION. (N.M. Terr. Laws 1907, 37th assy., ch. 62/pp. 123-124)
25 February 1909
CURRY created by New Mexico Territory from QUAY and ROOSEVELT. (N.M. Terr. Laws 1909, 38th assy., ch. 6/pp. 9-13)
17 March 1909
Territorial Legislature authorized SIERRA to gain from SOCORRO in "An Act to abolish the county of Sierra. . . . And creating a new county with different boundaries with the name of Sierra." Change was not approved by the U.S. Congress, as required by The Organic Act for the Territory of New Mexico (1850) [no change]. (N.M. Terr. Laws 1909, 38th assy., ch. 61/pp. 160-166; U.S. Stat., vol. 9, ch. 49[1850], sec. 7/p. 449; Coan, p. 19)
18 March 1909
LINCOLN exchanged with SOCORRO. (N.M. Terr. Laws 1909, 38th assy., ch. 112/pp. 326-327)
06 January 1912
The state of New Mexico was admitted to the Union with 26 counties: BERNALILLO, CHAVES, COLFAX, CURRY, DOŅA ANA, EDDY, GRANT, GUADALUPE, LINCOLN, LUNA, McKINLEY, MORA, OTERO, QUAY, RIO ARRIBA, ROOSEVELT, SAN JUAN, SAN MIGUEL, SANDOVAL, SANTA FE, SIERRA, SOCORRO, TAOS, TORRANCE, UNION, and VALENCIA. New Mexico Territory eliminated. (U.S. Stat., vol. 34, Part 1, [ch. 3335 /p. 267])
12 March 1917
GRANT boundaries with SOCORRO and SIERRA redefined [no mappable change]. (N.M. Laws 1917, 3rd reg. sess., ch. 57/pp. 178-179)
08 June 1917
DE BACA created from CHAVES, GUADALUPE, and ROOSEVELT; ROOSEVELT gained from CHAVES. (N.M. Laws 1917, 3rd reg. sess., ch. 11/pp. 41-48)
LEA created from CHAVES and EDDY. (N.M. Laws 1917, 3rd reg. sess., ch. 23/pp. 108-110)
01 January 1920
HIDALGO created from GRANT. (N.M. Laws 1919, 4th reg. sess., ch. 11/pp. 11-12)
10 June 1921
HARDING created from MORA and UNION. (N.M. Laws 1921, 5th reg. sess., ch. 48/pp. 106-107)
01 July 1921
CATRON created from SOCORRO. (N.M. Laws 1921, 5th reg. sess., ch. 28/pp. 37-45)
13 March 1923
WASHINGTON (now QUAY) created from all of QUAY; QUAY eliminated. WASHINGTON existed for only one day before being renamed QUAY. This act and its companion the following day circumvented the constitutional prohibition against changing county boundaries by special or local law. (N.M. Laws 1923, 6th reg. sess., ch. 141/pp. 278-281)
JEFFERSON (now SAN MIGUEL) created from HARDING, Non-County Area 3, and all of SAN MIGUEL; Non-County Area 3 and SAN MIGUEL eliminated. JEFFERSON existed for only one day before being renamed SAN MIGUEL. This act and its companion the following day circumvented the constitutional prohibition against changing county boundaries by special or local law. (N.M. Laws 1923, 6th reg. sess., ch. 142/pp. 281-283)
14 March 1923
WASHINGTON renamed QUAY. This act and its predecessor circumvented the constitutional prohibition against changing county boundaries by special or local law. (N.M. Laws 1923, 6th reg. sess., ch. 150/p. 331)
JEFFERSON renamed SAN MIGUEL. This act and its predecessor circumvented the constitutional prohibition against changing county boundaries by special or local law. (N.M. Laws 1923, 6th reg. sess., ch. 151/p. 331)
18 March 1927
Legislature authorized the eliminations of CATRON and SOCORRO by the creation of RIO GRANDE (proposed) and the expansion of GRANT; also authorized changing the name of RIO GRANDE to SOCORRO. These acts attempted to circumvent the constitutional prohibition against changing county boundaries by special or local law and the attorney general filed action to prevent implementation of the statutes. Proposal failed on 3 April 1928 when the New Mexico Supreme Court ruled the act unconstitutional [no change]. (N.M. Laws 1927, 8th reg. sess., chs. 185-186/pp. 457-464; N.M. Constitution 1910, art. IV, sec. 2, in Swindler, 7:102-103; "State ex rel. Dow v. Graham," in N.M. Reports, 33:504-519; N.M. Stat. 1978, ch. 4, pamphlet 11, 4-28-1 "Socorro County Laws" 1927, ch. 185; Coan reprint, 20)
16 March 1949
LOS ALAMOS created from SANDOVAL and SANTA FE. A small area of SANDOVAL was separated from the rest of the county, and SANDOVAL remained in two parts as of 2000. (N.M. Laws 1949, 19th reg. sess., ch. 134/pp. 319-321)
07 March 1950
SIERRA gained from SOCORRO by a special election. (N.M. Compiled Stat. 1999, ch. 4, article 27, sec. 1/p. 43; election certificate filed with the Sierra County Clerk on 13 September 1951)
17 March 1981
CIBOLA created from VALENCIA. (N.M. Laws 1981, 35th reg. sess., ch. 24/pp. 76-80)
05 April 1995
Legislature authorized the creation of SOUTH VALLEY (proposed) from BERNALILLO, dependent on a vote in the general election of 5 November 1996. Proposal failed in referendum [no change]. (N.M. Laws 1995, 42d reg. sess., ch. 85/pp. 726-736; N.M. Stat. 1978 Annotated, 2001 Cumulative Supplement, ch. 4, pamphlet 11, article 1A, p. 1)