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Jeffrey B. Lewis, Brandon DeVine, and Lincoln Pritcher with Kenneth C. Martis

The webpage for this project can be found athttp://cdmaps.polisci.ucla.edu.

These repositiories provides digital boundary definitions in GeoJsonformat for every U.S. Congressional District in use between 1789 and2012. These were produced as part of NSF grant SBE-SES-0241647 between2009 and 2013.

The current release of these data is experimental. We have had done agood deal of work to validate all of the shapes. However, it is quitelikely that some irregulaties remain. Please emailjblewis@ucla.eduwith questions or suggestions for improvement. We hope to have aticketing system for bugs and a versioning system up soon. Thedistrict definitions currently available should be considered apre-release version.

Many districts were formed by aggregragating complete county shapesobtained from the National Historical Geographic Information System(NHGIS) project and the Newberry Library's Atlas of Historical CountyBoundaries. Where Congressional Districts boundaries did not coincidewith county boundaries districts shapes were constructeddistrict-by-district using a wide variety of legal and cartographicresources. Detailed descriptions of how particular districts wereconstructed and the authorities upon which we relied are available (atthe moment) by request.

The Principal Investigator on the project was JeffreyB. Lewis. Brandon DeVine and Lincoln Pitcher researched districtdefinitions and produced thousands of digital district boundaries. Theproject relied heavily on Kenneth C. Martis' The Historical Atlas ofUnited States Congressional Districts: 1789-1983. (New York: The FreePress, 1982). Martis also provided guidance, advice, and sourcematerials used in the project.

Jeffrey B. Lewis, Brandon DeVine, Lincoln Pitcher, and KennethC. Martis. (2013) Digital Boundary Definitions of U.S. CongressionalDistricts, 1789-2012. [Data file and code book]. Retrieved fromhttp://cdmaps.polisci.ucla.edu on [date of download].

If you use the shapes in your research, please send along an emaildescribing your project and giving a citations to resulting to workingpapers and publications Geographic information

The district definitions are organized by state and the range ofCongresses in which they were operative. Each unique district hasbeen given a unique identifier with the following format SSNNBBBEEEwhere SS is the state fips code, NN is the district number, BBB is thenumber of first Congress in which that district was used and EEE isthe last Congress in which that district was used.

District geographic definitions are encoded in US Census standardunprojected format using the NAD83 coordinate datum (PostGIS SRID4269). The PROJ.4 string is:

+proj=longlat +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +no_defsDownload

The files provide districts shapes for each Congress in ERSI'sShapefile format. The current files are version 1.00 (June 20, 2013).

Our enumeration of Congressional districts in effect in a particularCongress follows Martis. At large districts are numbered "0". In a fewcases, shapes describing Indian territories within states during the18th and early 19th centuries are included in the shape files. Theseterritories are always assigned district number "-1". TheCongressional districts in the shape files match districts containedin rollcall voting data files and Congressional roster files availableon Keith Poole's Voteview site here and here. There are a very fewinstances in which there is no member representing a particulardistrict in a particular Congress (a file enumerating all knowndiscrepancies between the Voteview data and these shapes is availablehere.

Starting with the 103rd Congress, district boundary files are producedby the US Census and we rely on those shapes for Congresses beginningwith the 103rd. US Census Tigerline files associated the 1990Decennial Census were used to construct districts from the 98th to the102nd Congress (except where noted in the documentation filesbelow). For Congresses between the 1st and the 97th, districtboundaries were formed in one of two ways. For districts that weremade up of collections of complete counties, historical countyboundaries from NHGIS or were dissolved to form districtboundaries. Districts that divided one or more counties were formed ona case-by-case basis. Sources relied upon for these districts aredescribed in the documentation files below.

Access to Excel .xlsx files containing references and documentationrelated to how each district shape was drawn are available at thehttp://cdmaps.polisci.ucla.edu. Access to these files islimited due to possible copyright issues (some of the documentationfiles include images of maps). To obtain access to these materials forresearch purposes, please emailjblewis@ucla.edu. File names indicatethe state and range of Congresses covered by districts described in aparticular documentation file. [Click to show available documentationfiles]

Copyright Jeffrey B. Lewis, 2013.