These large-scale maps show and label all census blocks within a county (or county equivalent). In addition to state (or state equivalent) and county, these maps show the boundaries, names, and codes for American Indian/Alaska Native areas, Hawaiian home lands, county subdivisions, consolidated cities, places, and census tracts. These maps show and label state legislative districts (SLDs) and voting districts (VTDs)–the geographic entities that the states submitted during their participation in the early phases of the Census Redistricting Data Program. The P.L. 94-171 County Block Maps also show and label base features, such as roads, railroads, and hydrography. The intent of this map series is to map each county on the fewest number of map sheets possible and at the maximum practical scale, depending on the size and shape of the county and the distribution of census blocks. Census block density affects the display of block numbers and feature labels. Each county is covered by one or more parent map sheets at a single scale. Inset map sheets at larger scales are created as required to show the map content described above. An index map sheet showing the sheet configuration is created for all counties requiring more than one parent sheet. The map sheet size is 36 by 32 inches.

Each county's map is accompanied by three semicolon-delimited map sheet relationship text files:

1. Census Block to Map Sheet File (BLK2MS) - This text file includes a record for each census block within the county and a list of all the map sheets where that block appears. In addition to the 15-character census block full code, each record contains the codes for the corresponding state, county, census tract, census block, place, county subdivision, consolidated city, federally recognized American Indian reservation and/or off-reservation trust land, state legislative district (upper and lower chamber), and voting district for that block.
2. SLD to Map Sheet File (SLD2MS) – This text file includes a record for each SLD (upper chamber [SLDU] and lower chamber [SLDL]) wholly or partially within the county and a list of all the map sheets where that SLD appears. In addition to the 5-character SLD full code, each record contains the codes for the corresponding state, county, and SLD, as well as the SLD name.
3.  VTD to Map Sheet File (VTD2MS) – This text file includes one record for each VTD within the county and a list of all the map sheets where that VTD appears. In addition to the 11-character VTD full code, each record contains the codes for the corresponding state, county, and VTD, as well as the VTD name.

A catalog file including the file name, entity name, and total number of map sheets is provided in the directory for each state. The map file (PDF) and associated text files are in county-based directories.

Map Viewing Tips: These maps were designed to be viewed with Adobe Reader (version 6 or later), which is available free from Adobe. These maps are large and use complex symbology, such as wave pattern fill for water bodies. If a browser opens them in another PDF reader, the screen display may not accurately reproduce the map. For best viewing in Adobe Reader, uncheck the “Enhance thin lines” option, found under the Edit tab: Preferences > Category: Page Display > Rendering section.