Introduction

Census block groups, as defined by the US Census Bureau, are statistical geographic subdivisions of census tracts, typically containing 600 to 3,000 people. They are composed of clusters of census blocks and are used to tabulate and present census data. The boundaries are generally stable but can be altered based on visible features like streets, roads, or streams, and are always contained within a single county and census tract.

• Population: Generally between 600 and 3,000 people.
• Structure: A collection of census blocks that are within the same census tract.
• Numbering: Each block group has a unique identifier, which is the first digit of the census blocks it contains (e.g., block group 3 contains all blocks starting with the number 3).
• Boundaries: Follow features like streets, roads, and rivers, and do not cross county or census tract boundaries.
• Data usage: The smallest geographic unit for which the American Community Survey (ACS) provides 5-year estimates.

The map and table below give geographic data on the 3925 census block groups in Alabama. The land and water areas are given in square miles.

Map

In the map below, the counties can be added as an area layer using the layer control, and the census-designated central points can be added as a point layer. Click on a feature to view summary information about the feature.

Tables

Block Groups

Click on a row to see the corresponding block group highlighted in green in the map. For small block groups, you may have to zoom to see the highlighting. Click on a row again to de-select.

Summary by Tract

Summary by County