2011 Redistricting Reference Data


A large amount of reference data is used to draw political districts. This data can be divided into two main groups: numeric and geographic. The numeric component includes items such as population and voter registration values. The geographic component includes features such as roads, rivers, and political boundaries that can be graphically displayed as features on a map.

The numeric data matches up with the geographic data at several different levels. The main levels of interest in district drawing are counties, voting tabulation districts (VTDs), and census blocks. These three main levels have a nesting relationship. In other words, counties are comprised of VTDs that, in turn, are comprised of census blocks. Each level covers the entire territory of the state, such that there is no point within the state's boundaries that cannot be assigned to each of the three levels.

All information on this page corresponds with the redistricting database compiled by the General Assembly in March of 2011.

There were three main types of numeric data in the 2011 redistricting database:

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 maintains a statewide voter registration system called the State Elections Information Management System, or SEIMS. Weekly SEIMS extracts are posted, from which it is possible to determine voter characteristics by VTD. The 2011 redistricting database contains breakdowns for age group, gender, race, ethnicity, and party affiliation. The voter registration data included in the database was processed to correspond with voters eligible to vote in the 2010 general election.

Election Returns Data - also provided by the State Board of Elections. Results for 2006 and earlier are available by voter precinct. Beginning in 2008, election returns are available by VTD. The 2011 redistricting database contains various contests from 2004 through 2010. See the field layout definition for details.

Complete numeric datasets, as processed for use in the General Assembly's redistricting system, are linked below for download. The field layout definition is required to interpret the field headings. See the data processing notes document for technical details. The "block level keys" table is useful for establishing relationships between the different geographic levels. The numeric data is also appended to each of the corresponding geographic layers, available for download in the following section. Note that the General Assembly's redistricting system is census block-based. All data items therefore have to reconcile to that lowest level of geography. Although registration and elections data are available at all geographic levels, they are most reliable at the VTD and county levels since the original data was VTD-based.

The geographic data in the General Assembly's redistricting system is based on the 2010 TIGER/Line Shapefiles provided by the US Census Bureau. Below are links to various statewide layers derived from that dataset. These files are intended for use with Geographic Information System (GIS) software. Layers are projected in NC State Plane, NAD83, meters.

Tab-Delimited Text (*.tab) is a simple text format consisting of values separated by tabs. It is easily imported into spreadsheet and database programs, with each line of the file corresponding to a table row, and each item in a line corresponding to a table column. It can also be viewed with text editor programs such as NotePad or WordPad, provided the file isn't too large.

Access Database (*.accdb). This is a database format used by Microsoft Access, starting with Access 2007.

File Geodatabase. This is a spatial data format created by ESRI. File geodatabases contain geographic layers and are used with geographic information system (GIS) software. Each geodatabase is comprised of a directory with a ".gdb" extension containing a large number of individual files.

ZIP. Due to large size, some of the files linked from this site have been compressed or "zipped". In addition to native support in some operating systems, a variety of commercial and open source programs exist that can extract ".zip" files.