Authority
The U.S. Office of Management and Budget (OMB) maintains and updates statistical area classifications.
Terminology
Names of statistical areas have changed since they were first designated in 1949.
- In 1949 standard definitions of metropolitan areas were issued under the designation "standard metropolitan area"
- In 1959 the term was changed to "standard metropolitan statistical area"
- In 1983 it was changed to "metropolitan statistical area"
- In 1990 the collective term "metropolitan area" became effective and included metropolitan statistical areas , consolidated metropolitan statistical areas, and primary metropolitan statistical areas
- In 2000 the collective term was changed to "core-based statistical areas" and encompassed metropolitan statistical areas and micropolitan statistical areas, which may be combined to form combined statistical areas.
Standards
Currently defined statistical areas are based on standards published in the Federal Register on July 2015. Because of historical changes in geographic definitions, users must be cautions in comparing statistical area data from different dates.
- Metropolitan and micropolitan statistical areas are defined in terms of whole counties
- One or more principal cities are identified within each metropolitan and micropolitan statistical area
- These cities are the population and employment centers and are used in titling the areas
Metropolitan statistical areas:
- Have at least one urbanized area of 50,000 or more population and
- May include adjacent counties that have a minimum of 25 percent of workers commuting to the central counties of the metropolitan statistical area.
Micropolitan statistical areas:
- Have at least one urban cluster of at least 10,000 but less than 50,000 population and
- May include adjacent counties that have a minimum of 25 percent or workers commuting to the central counties of micropolitan statistical area.
Combined statistical areas:
- Are composed of metropolitan statistical areas and micropolitan statistical areas in various combinations
- Are automatically designated for adjacent areas with an employment interchange of 25 percent or more
- In adjacent areas with an employment interchange of at least 15 percent but less than 25 percent, designation of combined statistical areas is based on local opinion, as expressed through the Congressional delegations
- Should not be ranked or compared with individual metropolitan and micropolitan statistical areas, because combined statistical areas represent groups of metropolitan and micropolitan statistical areas
Deliniations - Iowa Metropolitan Statistical Areas
Iowa has nine metropolitan statistical areas made up of twenty-one Iowa counties and eleven counties in other states (2015):
- Ames, IA - Boone county (2018), Story county (2003)
- Cedar Rapids, IA - Benton county (2003), Jones county (2003), Linn county (1950)
- Davenport-Moline-Rock Island, IA-IL - Henry county (IL) (1963), Mercer county (IL) (2003), Rock Island county (IL) (1950), Scott county (IA) (1950)
- Des Moines-West Des Moines, IA - Dallas county (1983), Guthrie county (2003), Jasper (2018), Madison county (2003), Polk county (1950), Warren county (1973)
- Dubuque, IA - Dubuque county (1960)
- Iowa City, IA - Johnson county (1981), Washington county (2003)
- Omaha-Council Bluffs, NE-IA - Harrison county (IA) (2003), Mills county (IA) (2003), Pottawattamie county (IA) (1950), Cass county (NE) (1993), Douglas county (NE) (1950), Sarpy county (NE) (1950), Saunders county (NE) (2003), Washington county (NE) (1983)
- Sioux City, IA-NE-SD - Woodbury county (IA) (1950) , Dakota county (NE) (1963), Dixon county (NE) (2003), Union county (SD) (2003)
- Waterloo-Cedar Falls, IA - Black Hawk county (1960), Bremer county (2003), Grundy county (2003)
Deliniations - Iowa Micropolitan Statistical Areas
Iowa has seventeen micropolitan statistical areas made up of nineteen Iowa counties and three counties in other states (2015):
- Burlington, IA-IL - Henderson county (IL), Des Moines county (IA)
- Carroll, IA - Carroll county
- Clinton, IA - Clinton county
- Fairfield, IA - Jefferson county
- Fort Dodge, IA - Webster county
- Fort Madison-Keokuk, IA-IL-MO - Hancock county (IL), Lee county (IA), Clark county (MO)
- Marshalltown, IA - Marshall county
- Mason City, IA - Cerro Gordo county, Worth county
- Muscatine, IA - Muscatine county
- Oskaloosa, IA - Mahaska county
- Ottumwa, IA - Davis county, Wapello county
- Pella, IA - Marion county
- Spencer, IA - Clay county
- Spirit Lake, IA - Dickinson county
- Storm Lake, IA - Buena Vista county
Deliniations - Iowa Combined Statistical Areas
Iowa has four combined statistical areas (2015):
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Cedar Rapids-Iowa City, IA - Cedar Rapids, IA metropolitan statistical area and Iowa City, IA metropolitan statistical area
- Davenport-Moline, IA-IL - Clinton, IA micropolitan statistical area, Davenport-Moline-Rock Island, IA-IL metropolitan statistical area, and Muscatine, IA micropolitan statistical area
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Des Moines-Ames-West Des Moines, IA - Ames metropolitan statistical area, Boone, IA micropolitan statistical area, Des Moines-West Des Moines, IA metropolitan statistical area and Newton micropolitan statistical area.
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Omaha-Council Bluffs-Fremont, NE-IA - Fremont, NE micropolitan statistical area and Omaha-Council Bluffs, NE-IA metropolitan statistical area
- Oskaloosa-Pella, IA - Oskaloosa, IA micropolitan statistical area and Pella, IA micropolitan statistical area
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Sioux City-Vermillion, IA-NE-SD - Sioux City, IA-NE-SD metropolitan statistical area and Vermillion, SD micropolitan statistical area
More Information
For information about statistical area standards, definitions, and concepts, see: