A census block is the smallest geographic unit used by the

United States Census Bureau The United States Census Bureau (USCB), officially the Bureau of the Census, is a principal agency of the U.S. Federal Statistical System, responsible for producing data about the American people and economy. The Census Bureau is part of th ...

for tabulation of 100-percent data (data collected from all houses, rather than a sample of houses). The number of blocks in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

, including

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...

, for the 2010 Census was 11,155,486. Census blocks are grouped into block groups, which are grouped into

census tract A census tract, census area, census district or meshblock is a geographic region defined for the purpose of taking a census. Sometimes these coincide with the limits of cities, towns or other administrative areas and several tracts commonly exis ...

s. There are on average about 39 blocks per block group. Blocks typically have a four-digit number; the first number indicates which block group the block is in. For example, census block 3019 would be in block group 3. Blocks are typically bounded by roads and highways, town/city/county/state boundaries, creeks and rivers, etc. In cities, a census block may correspond to a

city block A city block, residential block, urban block, or simply block is a central element of urban planning and urban design. A city block is the smallest group of buildings that is surrounded by streets, not counting any type of thoroughfare within t ...

, but in rural areas where there are fewer roads, blocks may be delimited by other features such as political boundaries, rivers and other natural features, as well as parks and similar facilities, etc. The population of a census block varies greatly. As of the 2010 census, there were 4,871,270 blocks with a reported population of zero,Nobody lives here: The nearly 5 million Census Blocks with zero population
/ref> while a block that is entirely occupied by an apartment complex might have several hundred inhabitants. Census blocks covering the entire country were introduced with the 1990 census. Before that, back to the

1940 census The United States census of 1940, conducted by the Census Bureau, determined the resident population of the United States to be 132,164,569, an increase of 7.3 percent over the 1930 population of 122,775,046 people. The census date of record w ...

, only selected areas were divided into blocks.

References

{{USCensus Geography United States Census Bureau geography