Data Dictionary
This document contains the Geographic Information System (GIS) data dictionary for the Comptroller of the Treasury, Office of Local Government redistricting program. The data dictionary presented here is applicable to all county redistricting data sets included in the Office of Local Government's GIS, but may be utilized to assist in other applications such as urban growth planning, site selection, economic development, and others.
All shapefiles were created from the U.S. Census Bureau's 2000 Redistricting version of the T.I.G.E.R. line files. T.I.G.E.R. (Topologically Integrated Geographic Encoding and Referencing) is the Census Bureau's digital base map used for a variety of programs, including the 2000 Redistricting Data Program. See http://www.census.gov/geo/www/tiger/index.html for more details. All shapefiles were created and are maintained at a county level and have the following characteristics
Map units: feet
Coordinate system: Tennessee State Plane NAD83(90)
Projection: Lambert Conformal Conic
ArcView Shapefiles
A shapefile is a proprietary file format developed by Environmental Systems Research Institute (ESRI) and can be utilized in a number of GIS software products including ArcView. In ArcView, shapefiles (.shp), correspond to themes that are managed in a View, but actually include a number of other ancillary files (.shx, .dbf, and others). For purposes of this document, the term "shapefile" is used to describe ArcView themes and their associated data files.
Each county data set includes the following shapefiles:
Block_lines
Blocks
City00
County
Roads
Railroads (not present in all counties)
Water_lines
Water_polys
Composite_lines
Composite_polys
In addition to the TIGER files, the U.S. Census Bureau as required by Public Law 94-171, provides states with official population data used for redistricting. The Office of Local Government (OLG) is designated as one of the official recipients for this information.
The OLG has customized the standard PL 94-171 population data set as delivered by the census
bureau. The following table shows the relationship between the official census race and ethnicity
categories and the OLG customized race and ethnicity categories used for redistricting.
| Census Race & Ethnicity Categories | OLG Race & Ethnicity Categories |
| White | Whpop |
| Black or African American | Blpop |
| American Indian | Otherpop |
| Asian | |
| Native Hawaiian and other Pacific Islander | |
| Some other race | |
| Two or more races | |
| Hispanic (of any race) | Hispop |
Simply put, American Indian, Asian, Native Hawaiian, "Some other race", and "Two or more races", are merged into the OLG category, Otherpop. The population totals for these individual race categories were not significant enough to include them in our final data sets. These same categories exist for voting age population (whpop18, blpop18, otherpop18, and hispop18).
*Note: Hispanic is not a racial category. It is an ethnicity. As a result, Hispanic population is not a subset of total population. In other words, adding only whpop, blpop, and otherpop will equal the total population. Hispop is not included in this equation.
Database Shapefiles
The following list contains a description for each shapefile and highlights some of its
corresponding attributes.
| Shapefile Name: | Block_lines | ||||
Description: contains only line features of census block boundaries. A cartographic layer, block_lines is used to symbolize census block boundaries as roads, railroads, water features, powerlines, ridgelines, and some non-visible boundaries.
Significant attributes: (block_lines.dbf)
TLID - Tiger/line ID, a permanent record number that uniquely identifies each line segment.
CFCC - (census feature classification code) provides an alphanumeric code for each line feature, used to classify roads, railroads, water, and other linear features.
See page 70 on http://www.census.gov/geo/www/tiger/tiger2k/tiger2k.pdf for details.
Name - provides a feature name for a majority of the block boundaries (i.e. Main St., Mill Creek,
escarpment, etc.) although some are blank.
| Shapefile Name: | Blocks | ||||
Description: contains census blocks for an entire county. Unlike block_lines, this shapefile has total population and voting age totals by race and ethnicity.
Significant attributes: (blocks.dbf)
Stfid - unique identifier for each block, consists of state, county, tract, and block number.
Totalpop - contains the total population for each individual census block and is the key item or field used in redistricting
Whpop - total white population for each individual census block.
Blpop - total black population for each individual census block.
Otherpop - total of other racial population (see table on page 2) for each individual census block.
Hispop - total Hispanic population for each individual census block.
Totalpop18 - total voting age population for each individual census block
Whpop18 - total voting age white population for each individual census block.
Blpop18 - total voting age black population for each individual census block.
Otherpop18 - total of other voting age racial population for each individual census block.
Hispop18 - total Hispanic voting age population for each individual census block.
|
Shapefile Name: |
City00 | ||||
Description: (an abbreviation for 2000 cities, towns, or census designated places (CDP) ) this shapefile is used to tabulate 2000 population totals for existing incorporated or census designated places. While not essential to county redistricting, it may provide officials with an additional data resource when drawing new plans.
Significant attributes: (city00.dbf)
Totalpop - total population for each city, town, or CDP.
Whpop - total white population for each city, town, or CDP.
Blpop - total black population for each city, town, or CDP.
Otherpop - total of other racial population (see table on page 2) for each city, town, or CDP.
Hispop - total Hispanic population for each city, town, or CDP.
Totalpop18 - total voting age population for each city, town, or CDP.
Whpop18 - total voting age white population for each city, town, or CDP.
Blpop18 - total voting age black population for each city, town, or CDP.
Otherpop18 - total of other voting age racial population for each city, town, or CDP.
Hispop18 - total Hispanic voting age population for each city, town, or CDP.
Name - lists the name of the city, town, or CDP.
| Shapefile Name: | County | ||||
Description: this shapefile is used to tabulate 2000 population totals for a county.
Significant attributes: (county.dbf)
county - three digit county number (i.e. 001,003,005)
Totalpop - total population for each county
Whpop - total white population for each county.
Blpop - total black population for each county.
Otherpop - total of other racial population (see table on page 2) for each county.
Hispop - total Hispanic population for each county.
Totalpop18 - total voting age population for each county.
Whpop18 - total voting age white population for each county.
Blpop18 - total voting age black population for each county.
Otherpop18 - total other voting age racial population for each county.
Hispop18 - total Hispanic voting age population for each county.
Name - contains the name of the county.
| Shapefile Name: | Roads | ||||
Description: contains only line features of county roads. A cartographic layer, roads is used to symbolize interstate highways, major roads, local roads, and other roads.
Significant attributes: (roads.dbf)
TLID - Tiger/line ID, a permanent record number that uniquely identifies each line segment.
CFCC - (census feature classification code) provides an alphanumeric code for each line feature.
See page 70 on http://www.census.gov/geo/www/tiger/tiger2k/tiger2k.pdf for details.
Name - provides a feature name for a majority of the roads (i.e. Main St., I-40, etc.) although
some are blank.
| Shapefile Name: | Railroads | ||||
Description: contains only line features of county railroads. Railroad shapefiles are not present in all county data sets, as not all Tennessee counties have railroads.
Significant attributes: (railroads.dbf)
TLID - Tiger/line ID, a permanent record number that uniquely identifies each line segment.
CFCC - (census feature classification code) provides an alphanumeric code for each line feature.
See page 70 on http://www.census.gov/geo/www/tiger/tiger2k/tiger2k.pdf for details.
FeName - provides a feature name for a majority of the railroads (i.e. Southern Csx, Tennessee
railroad, etc.) although some are blank.
| Shapefile Name: | Water_lines | ||||
Description: contains only line features of rivers, creeks, and lake outlines.
Significant attributes: (water_lines.dbf)
TLID - Tiger/line ID, a permanent record number that uniquely identifies each line segment.
CFCC - (census feature classification code) provides an alphanumeric code for each line feature.
See page 70 on http://www.census.gov/geo/www/tiger/tiger2k/tiger2k.pdf for details.
FeName - provides a feature name for a majority of the linear water features (i.e. Mill creek,
Buffalo River, etc.) although some are blank.
| Shapefile Name: | Water_polys | ||||
Description: contains only area features of ponds, lakes, some large rivers, etc.
Significant attributes: (water_polys.dbf)
CFCC - (census feature classification code) provides an alphanumeric code for each feature.
See page 70 on http://www.census.gov/geo/www/tiger/tiger2k/tiger2k.pdf for details.
LandName - provides a feature name for a majority of the water features (i.e. Mill pond, Center
Hill Lake, Tennessee River, etc.) although some are blank.
|
Shapefile Name: |
Composite_lines | ||||
Description: contains all linear features of a county and is the parent shapefile to block_lines.
Significant attributes: (composite_lines.dbf)
TLID - Tiger/line ID, a permanent record number that uniquely identifies each line segment.
CFCC - (census feature classification code) provides an alphanumeric code for each line feature.
See page 70 on http://www.census.gov/geo/www/tiger/tiger2k/tiger2k.pdf for details
FeName - provides a feature name for a majority of linear features (i.e. Edmondson Pike, Seven Mile creek, ) although some are blank.
| Shapefile Name: | Composite_polys | ||||
Description: contains all area features of a county and is the parent shapefile to blocks
Significant attributes: (composite_polys.dbf)
Polyid, Cenid - the combination of these two fields represent a unique identifier for each polygon.