North Carolina General Assembly - NCGA

Redistricting Data

A large amount of base data is needed to draw political districts. There are two main classes of data - geographical and statistical. The geographical data component includes features such as roads, rivers, and political boundaries that can be graphically displayed as features on a map. The statistical data component includes items such as population and voter registration values. The statistical data matches up with the geographic data at several different levels. The main levels of interest in district drawing are counties, voter precincts, and census blocks. These three main levels have a nesting relationship, in other words counties are comprised of voter precincts that, in turn, are comprised of census blocks. Each level covers the entire territory of the state, that is, there is no point within the state's boundaries that cannot be assigned to each of the three levels.

Geographical Data

The current geographical data in the General Assembly's redistricting system is based on the "UA Census 2000 TIGER/Line Files" provided by the US Census Bureau. Below are links to various statewide layers extracted from TIGER. The voter precinct layer, though originally derived from 2000 TIGER, has been updated to reflect precinct changes through the last redistricting database build in October of 2003. These files can be used with geographic information system software. Layers are in shapefile format. The shapefiles are projected in the North Carolina State Plane coordinate system. Units are in meters. The projection is based on North American Datum 1983. Due to their relatively large sizes, and the fact that each "shapefile" consists of a group of files, all layers have been compressed.

Census Tabulation Units:

Political Units:

Infrastructure:

Physical Features:

Statistical Data

There are three main types of statistical data in our system:

Population Data - by April 1st of the year following each decennial census, the US Census Bureau provides Public Law 94-171 data to each of the states. This data corresponds with block level geography, the lowest level tabulated by the Census Bureau, and that at which districts are ultimately defined. The Public Law 94-171 data contains only race and ethnicity breakdowns of total and voting age populations.
Voter Registration Data - the State Board of Elections provided registration information for all voter precincts in the state as recorded in their State Elections Information Management System (SEIMS). In this data set, current as of December 2002, registered voters are broken down by party, race, gender, and age group.
Election Returns Data - also provided by the State Board of Elections at the voter precinct level, information is included for various contests from the 2000 and 2002 general elections. Note that county boards of elections are not currently required to report all votes at the precinct level. Each county has a county-wide "absentee/provisional" category. Since inclusion of these figures would tend to homogenize the precinct-level results, they were excluded from the database. Data on three non-statewide elections were included - US House, NC House, and NC Senate. Statewide redistricting requires that all data items be available statewide. For these contests, votes were therefore tabulated by party rather than by candidate and district.

Complete statistical data sets, as processed for use in the General Assembly's redistricting system, are linked below for download. The field layout definition is required to interperet the information. Also included is a "block level units key" which is useful for establishing relationships between the different geographic levels. All files are in tab-delimited format. Due to their relatively large sizes, four of the seven files have been compressed.

Please note that although registration and elections data are available at all levels for system consistency, they are most reliable at the precinct and county levels since the original data was precinct-based.