For each county or statistically equivalent entity, the Census Bureau's block maps show the greatest detail and most complete set of geographic information. These large scale maps depict the smallest geographic entities for which the U.S. Census Bureau presents data - the census block - by displaying the features that form block boundaries and the numbers that identify them. The intent of this map series is to produce a map for each county, on the smallest possible number of map sheets, at the maximum practical scale. The maps show the boundaries, names and codes for American Indian areas/Alaska Native areas/Hawaiian home lands, county sub-divisions, places, voting districts, census tracts, block groups, and census blocks. Base feature details, such as roads, railroads, and water features are also shown. Each entity will be covered by one or more parent sheets at a single scale and when necessary, by inset maps at larger scales. For entities that are mapped on two or more map sheets, an index map showing the map sheet configuration will also be produced.
FINDING THE MAPS YOU NEED:
Go to the appropriate county subdirectory and download or view on-line the county index map. The county index map will show the county boundaries and the boundaries of any places within the county. It also will have an overlay of a grid of squares. Each square represents the area covered by one of the maps for that county. Using this grid, you can determine which map or maps cover the area of interest. At the center of each grid square you will find a map sheet number. This number is also a part of the file name for the PDF file of the map(s). It is in the last three positions before ".pdf". For example - pb25001_004.pdf is sheet number 4, shown in grid number 4 for Barnstable county, Massachusetts. With this information you can download or view the appropriate maps(s).
There may be instances in which the entire county is shown on a single County Block Map. For these counties, a single map file will appear in the appropriate county sub-directory. Download or view the map on-line. If there is more than one map file in the appropriate sub-directory, download or view the county index map on-line. A county sub-directory also may also have a parent sheet and one or more inset maps. In this case, there is no index sheet. Download or view the parent sheet to identify the inset maps.
File naming convention:
Source: U.S. Census Bureau
Cartographic Operations Branch
Last revised: March 01 2012