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History and Facts of Colorado Counties

Colorado Counties –

In 1861 the first Colorado counties were formed. They were AdamsArapahoeBoulderClear CreekConejosCostillaDouglasEl PasoFremontGilpinHuerfanoJeffersonLarimerParkPuebloSan MiguelSummit and Weld Counties.

List of Colorado Counties

Colorado is divided into 64 counties.

List of Old Former / Extinct Colorado Counties

Colorado has counties that no longer are in existence. A lot of these counties were established and disbanded within the 19th century; county borders have modified very little since 1900 in the vast most of states.

The below Colorado counties no longer exist:

?? County, Colorado

Created ? from ?. It was abolished ? and re-established as ? County on ?.

  • Arapahoe County, Kansas Territory, (1855-08-25 – 1861-01-29) was created but never organized. Reverted to unorganized territory when Kansas joined the Union.
  • Broderick County, Kansas Territory, (1859-02-07 – 1861-01-29) was split from Arapahoe County, but never organized. Reverted to unorganized territory when Kansas joined the Union.
  • Carbonate County – was a county that existed for only two days in 1879. Carbonate County was created by renaming it to Lake County.
  • El Paso County, Kansas Territory, (1859-02-07 – 1861-01-29) was split from Arapahoe County, but never organized. Reverted to unorganized territory when Kansas joined the Union.
  • Fremont County, Kansas Territory, (1859-02-07 – 1861-01-29) was split from Arapahoe County, but never organized. Reverted to unorganized territory when Kansas joined the Union.
  • Montana County, Kansas Territory, (1859-02-07 – 1861-01-29) was split from Arapahoe County, but never organized. Reverted to unorganized territory when Kansas joined the Union.
  • Oro County, Kansas Territory, (1859-02-07 – 1861-01-29) was split from Arapahoe County, but never organized. Reverted to unorganized territory when Kansas joined the Union.
  • Peketon County, Kansas Territory, (1859-02-07 – 1861-01-29) was created but never organized. Reverted to unorganized territory when Kansas joined the Union.
  • Arrappahoe County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • Cheyenne County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • El Paso County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • Fountain County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • Heele County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • Jackson County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • Jefferson County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • Montana County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • North County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • Park County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • Saratoga County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • St. Vrains County, Jefferson Territory, (November 1859 – 1861-02-28) was one of the 12 counties created by the extralegal Territory of Jefferson.
  • Guadalupe County, Colorado Territory, (1861-11-01 – 1861-11-07) was one of the 17 original counties created by the Territory of Colorado. The county was renamed Conejos County after only six days.
  • Greenwood County, Colorado Territory, (1870-02-11 – 1874-02-06) was created from former Cheyenne and Arapaho tribal land and the eastern portion of Huerfano County. The county was abolished four years later, and its territory split between Elbert County and Bent County.
  • Platte County, Colorado Territory, (1872-02-09 – 1874-02-09) was created from the eastern portion of Weld County. The county was abolished two years later after organizers failed to secure voter approval, and the territory of the county was returned to Weld County.
  • Carbonate County, Colorado, (1879-02-08 – 1879-02-10). Lake County was renamed Carbonate County in 1879. Only two days later, Carbonate County was split into the new Chaffee County and the re-renamed Lake County.
  • Uncompaghre County, Colorado, (1883-02-27 – 1883-03-02). Ouray County was renamed Uncompaghre County for only four days in 1883.
  • South Arapahoe County, Colorado, (1902-11-15 – 1903-04-11) was one of three counties created from Arapahoe County in 1902. The name was changed back to Arapahoe County after five months.
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Map of Colorado County Boundary Changes from 1877 to 1988

This Interactive Map of Colorado Counties show the historical boundaries, names, organization, and attachments of every county, extinct county and unsuccessful county proposal from the creation of Colorado in 1877-1988.

Fun Facts about Colorado Counties

County Name Facts

The County names:

  • 0 of them named for Native American words or people,
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Counties by Year

  • ? County was the first county created on ?.
  •  The last county to be formed was ? County on ?.
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Facts for County Size

  • ? County (000 sq mi) is the largest county in Colorado.
  • ? County (000 sq mi) is the smallest county in Colorado.

Facts for County Population (2017 Est.)

  • ? County (000) is the most populated county in Colorado.
  • ? County (000) is the least populated county in Colorado.

Facts for Colorado Counties and Cities

Colorado’s 10 largest cities (2010) are:

  1. Birmingham (000) is in ? County and ? Counties
  2. Denver, Colorado Springs,  Aurora,  Fort Collins, Lakewood, Thornton,  Westminster,  Arvada,  Pueblo and  Centennial