Atlas of Historical County
Boundaries: Dataset
(U.S. Compilation:
Historical States and Territories)
READ ME
How to Cite the U.S. Files
Full citation information for each dataset can be found in the “Citation.PreferredStyle” in the Summary Metadata files. The Summary Metadata files are located in the Supplemental Texts folder included with all of the downloadable shapefiles. They may also be found at: http://publications.newberry.org/ahcbp/
Creative Commons License
The Newberry Library is the copyright holder.
These files are free for use under an Attribution-NonCommercial-ShareAlike Creative Commons License and may be downloaded from the Web site: http://publications.newberry.org/ahcbp/.
Organization of the Data
The data have been organized into folders containing shapefiles and sets of supplementary information.
Historical States and Territories—a single shapefile that contains the polygons of every different, mappable version of each state, territory or equivalent — together with the corresponding attribute table and metadata, from 3 September 1783 through 31 December 2000. All changes are dated to the day. The attribute table contains the state and territorial names, beginning and ending dates for each polygon, plus brief descriptions of the changes and citations to the sources for the changes.
Supplemental Texts—a set of HTML files that provide information meant to increase the convenience and efficiency of the user’s work with the shapefiles and datafiles.
Identification_Information
Data_Quality_Information
Spatial_Data_Organization_Information
Spatial_Reference_Information
Entity_and_Attribute_Information
Distribution_Information
Metadata_Reference_Information
How to use the Historical States and Territories
shapefile to create a state and territorial boundary shapefile as of a selected
date.
The Historical States and Territories shapefile contains separate polygons for each unique state and territory shape from 9 September 1783 through 31 December 2000. Due to the numerous changes that have occurred in state and territorial boundaries, the shapefile includes many overlapping polygons. Each polygon includes field values specifying the start and end dates for that particular shape.
ESRI’s ArcMap software provides two approaches for working with the Historical States and Territories shapefile, as described below:
1. Definition
Query Approach
Using ESRI’s ArcMap software, it is simple to create a map
of state and territorial boundaries as of any selected date. This is done by
entering an ArcMap definition query to restrict the shapefile to only those
state and territorial shapes in effect at your date. The shapefile can then be
viewed and queried, or it can be exported to a separate shapefile or feature
class for use in other applications. The procedure is as follows:
A. Bring the Historical States and Territories polygon shapefile into the ArcMap Table of Contents.
Launch ArcMap.
Click on the Add Data icon in the standard toolbar to open the Add Data dialog box.
Navigate to the polygon shapefile and add it to the map.
B. Enter a Definition Query to display the state and territorial boundaries as of a specific date.
Double-click on the polygon layer in the ArcMap table of contents to open the Layer Properties dialog box.
Select the Definition Query tab.
Click on the Query Builder button.
Enter (or Copy/Paste) the following text into the white box in the bottom of the Query Builder dialog. This particular query will display the state and territorial boundaries as of 12/31/1900. You can replace both instances of "19001231" with your date in YYYYMMDD format.
"START_N" <= 19001231 AND "END_N" >= 19001231
Click Verify to test whether the syntax is correct. If you receive an error message, check that this query text was entered correctly.
Click Save if you want to save this definition query for future use.
Click OK, then OK again for the query to go into effect.
The polygon layer will now display state and territorial boundaries as of 12/31/1900.
C. Create a
shapefile or feature class of the state and territorial boundaries as of a
specific date.
In the ArcMap table of contents, right-click on the polygon layer (which should contain the above definition query).
Select Data > Export Data to open the Export Data dialog box.
Select the "Export: All features" option.
Click on the Browse button. The Saving Data dialog box will appear.
To export the data as a shapefile:
Set the "Save as type" equal to "Shapefile"
Navigate to a directory and click Save.
To export the data as a feature class:
Set the "Save as type" equal to "Personal Geodatabase feature classes" or "SDE feature classes".
Navigate to an existing geodatabase and click Save.
Click OK to export the data.
The exported data will include only those features from the polygon shapefile that satisfy the definition query.
2. Time-Enabled
Layer Approach (ArcGIS 10)
With ArcGIS 10, ESRI introduced another approach for working with temporal or time-enabled data. The first step is to enable time on a layer in ArcMap:
A. Bring the Historical States and Territories polygon shapefile into the ArcMap Table of Contents.
Launch ArcMap.
Click on the Add Data icon in the standard toolbar to open the Add Data dialog box.
Navigate to the polygon shapefile and add it to the map.
B. Enable time for the Historical States and Territories polygon layer (ArcMap 10).
Double-click on the polygon layer in the ArcMap table of contents to open the Layer Properties dialog box.
Select the Time tab.
Check the box labeled Enable Time on this layer.
Make the following selections within the Time Properties frame:
Layer Time: Each feature has a start and end time field
Start Time Field: START_DATE
End Time Field: END_DATE
Field Format: <Date/Time>
Layer Time Extent: Click Calculate to populate.
Click OK for these choices to go into effect
Once time has been enabled for this layer, you can use the ArcMap Time Slider tool or the Animation Toolbar. See ArcGIS 10 Help for more information about working with temporal or time-enabled data.