The 2020 Census – Census Block Map Series, also referred to as the Geographic Unit (GU) block maps, is produced to support the 2020 Census data release. These large format, entity-based maps are produced in Adobe’s portable document format (PDF) and are georeferenced. Maps are created for the following geographic entities: American Indian/Alaska Native Areas/Hawaiian home lands, tribal subdivisions, counties (or county equivalents), county subdivisions, consolidated cities, places, subbarrios, and estates.

These large-scale maps show and label all census blocks within an entity. In addition to state (or state equivalent) and county (or county equivalent), 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 also show and label base features, such as roads, railroads, and hydrography. The intent of this map series is to map each entity on the fewest number of map sheets possible and at the maximum practical scale, depending on the size and shape of the entity and the distribution of census blocks. Census block density affects the display of block numbers and feature labels. Each entity 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 entities requiring more than one parent sheet. The map sheet size is 36 by 32 inches.

Each entity's map is accompanied by a Census Block to Map Sheet (BLK2MS) relationship file. This semicolon-delimited text file includes one record for each census block within the entity 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, and American Indian/Alaska Native/Hawaiian home land for that block.

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