The United States acquired part of the area that is now Colorado from France as part of the Louisiana Purchase in 1803; part from territory ceded by Mexico in 1848, and part from territory sold to the United States by the state of Texas in 1850. Colorado Territory was organized from parts of Kansas, Nebraska, New Mexico, and Utah territories on February 28, 1861, with generally the same boundary as the present state.

Although the territory had not yet been legally established, census data for Colorado are available beginning with the 1860 census. The 1860 population shown for Colorado is for the portion of Kansas Territory that was organized as Colorado Territory. The 1860 population shown for Colorado excludes an undetermined number of people enumerated as part of Nebraska and New Mexico territories. The portion of present-day Colorado in Utah Territory—the portion west of the Rocky Mountains—was not enumerated in 1860. The population of the entire legally established Kansas Territory (of which the enumerated area of Colorado was a part) in 1860 was 141,483.

Data for the legally established state of Colorado are available beginning with the 1880 census.

AMERICAN INDIAN AREAS

Colorado has two federally recognized American Indian reservations.

METROPOLITAN AND MICROPOLITAN STATISTICAL AREAS AND RELATED STATISTICAL AREAS

Colorado has seven metropolitan statistical areas, seven micropolitan statistical areas, and one combined statistical area.

COUNTIES

There are 64 counties in Colorado.  The cities and counties of Broomfield and Denver are consolidated city-county governments.  They are classified as municipal governments, rather than as county governments, because they operate primarily as cities.  In each of the remaining 62 counties, the governing body is the board of county commissioners.

COUNTY SUBDIVISIONS

There are 209 county subdivisions in Colorado. They are all census county divisions (CCDs), which are delineated for statistical purposes, have no legal function, and are not governmental units.  CCDs were first established in Colorado for the 1960 census.  Prior to 1960, the minor civil divisions used in the census were election precincts.

PLACES

Colorado has 458 places; 271 incorporated places and 187 census designated places (CDPs). The incorporated places consist of 75 cities and 196 towns.  Cities have a minimum population threshold of 2,000.  Towns may be reclassified as cities when they reach the minimum population threshold. 

CENSUS TRACTS/BLOCK GROUPS/BLOCKS

Colorado has 1,249 census tracts, 3,532 block groups, and 201,062 census blocks.

CONGRESSIONAL DISTRICTS

For the 111^th Congress (January 2009-January 2011), Colorado had seven congressional districts.  For the 113^th Congress (January 2013-January 2015), Colorado continues to have seven congressional districts as a result of reapportionment based on the 2010 Census.

SCHOOL DISTRICTS

Colorado has 178 unified school districts.

STATE LEGISLATIVE DISTRICTS

There are 35 state senate districts and 65 state house districts in Colorado.

URBAN AREAS

Colorado has 64 urban areas; 9 urbanized areas and 55 urban clusters.

ZIP CODE TABULATION AREAS

There are 526 ZIP Code tabulation areas (ZCTAs) in Colorado.

¹  Source:  U.S. Department of Commerce, Bureau of the Census, Fourteenth Census of the United States, 1923
²  Source:  U.S. Census Bureau, recomputation for historical county level data which relied upon aggregate county level population data with an estimated county centroid resulting in a possible error of up to one mile.
³  Source:  U.S. Department of Commerce, Bureau of the Census, Centers of Population for States and Counties, 1974
⁴  Source:  U.S. Census Bureau, Geography Division, recomputation from archived national block group/enumeration area data resulting in a possible error of up to 1,000 feet.
⁵  Source:  U.S. Census Bureau, Geography Division, recomputation from archived national block group data resulting in a possible error of up to 1,000 feet.
⁶  Source:  U.S. Census Bureau, computation from national block-level data