Colorado County Organization Timeline

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Colorado County Organization Timeline

The original seventeen Colorado counties were organized by an enabling act of the first Colorado Territorial Legislature on November 1, 1861. That initial organization lasted only six days and then changes to county names, county seats and boundaries started. This listing attempts to summarize the changes in the order they occurred. Bold print indicates founding date of the county.

The town following the county name in parenthesis was designated the initial county seat in the county enabling act. Later county seat changes are summarized by the year they occurred without worrying about pinpointing exact dates. 108 places have been designated as a seat of government for Colorado's 64 counties. Weld county holds the Colorado record for moving its county seat five times (St Vrain 1861-1868, Latham 1868-1870, Evans 1870-1874, Greeley 1874-1875, Evans 1875-1877 and finally Greeley again in 1877).

Colorado Territory


    Feb 28 - Colorado Territory authorized by Congress.

    Nov 1 - Original 17 counties organized and county seats designated were - Arapahoe (Denver), Boulder (Boulder), Clear Creek (Idaho Springs), Costilla (San Miguel), Douglas (Frankstown), El Paso (Colorado City), Fremont (Canon City), Gilpin (Central City), Guadalupe (Guadalupe), Huerfano (Autobees Ranch), Jefferson (Golden City), Lake (Oro City), Larimer (La Porte), Park (Tarryall), Pueblo (Pueblo), Summit (Parkville), and Weld (St. Vrain).

    Of these, only Clear Creek and Gilpin still have their 1861 borders.

    A large area of eastern Colorado north of the Arkansas River was reserved by the Federal Government as "Indian Land" and was not included in the original division of Colorado Territory into counties.

    Nov 7 - Guadalupe renamed Conejos.


      Golden City designated as Territorial Capital.

      Summit county seat moved to Breckenridge.


    Conejos county seat moved to Conejos.

    Costilla county seat moved to San Luis.

    Lake county seat moved to Lourette.


    Douglas county seat moved to California Ranch.


    Feb 9 - Las Animas (Trinidad) created from Huerfano.

    Dec 29 - Saguache (Saguache) created from Lake and Costilla.

    Lake county seat moved to Dayton.

    Park county seat moved to Buckskin.


    Clear Creek county seat moved to Georgetown.

    Territorial capital moved from Golden City to Denver.


    Huerfano county seat moved to Badito.

    Lake county seat moved to Granite.

    Larimer county seat moved to Fort Collins.

    Park county seat moved to Fairplay.

    Weld county seat moved to Latham.


    Reserve of Indian Lands abandoned.


    Feb 11 - Bent (Las Animas) created from Huerfano and former Indian lands.

    Feb 11 - Greenwood (Kit Carson) created from former Indian lands.

    Borders of Douglas, Fremont, Huerfano, Las Animas and Pueblo adjusted.

    Bent county seat moved to Boggsville.

    Weld county seat moved to Evans.


    Feb 9 - Platte (seat?) created from Weld.

    Bent county seat moved back to Las Animas.


    El Paso county seat moved to Colorado Springs.


    Feb 2 - Grand (Hot Sulpher Springs) created from Summit.

    Feb 2 - Elbert (Kiowa) created from Douglas.

    Feb 6 - Greenwood disolved. Split between Elbert and Bent.

    Feb 9 - Platte recinded (voter ratification failed).

    Feb 10 - Hinsdale (San Juan City) created from Lake, Conejos, and Costilla.

    Feb 10 - La Plata (Howardsville) created from Lake and Conejos.

    Feb 10 - Rio Grande (Del Norte) created from Costilla and Conejos.

    Herfano county seat moved to Walsenberg.
    (Move has been dated as early as 1872.)

    Douglas county seat moved to Castle Rock.

    Weld county seat moved to Greeley.


    Bent county seat moved to the "new" Las Animas on the railroad.

    Hinsdale county seat moved to Lake City.

    Weld county seat moved back to Evans.


    Jan 31 - San Juan (Silverton) created from Lake.

    Jefferson county seat Golden City renamed Golden.

    La Plata county seat moved to Parrott City.

State of Colorado


    Aug 1 - Colorado becomes a state with 26 counties.


    Jan 18 - Ouray (Ouray) created from Hinsdale and Lake.

    Jan 29 - Routt (Hayden) created from Grand.

    Mar 9 - Custer (Ula) created from Fremont.

    Mar 9 - Gunnison (Gunnison) created from Lake.

    Weld county seat moved back to Greeley.


    Custer county seat moved to Rosita

    Routt county seat moved to Hahns Peak.


    Feb 8 - Carbonate (Granite) created by renaming Lake.

    Feb 10 - Chaffee (Granite) created from Carbonate.

    Feb 10 - Lake (Leadville) recreated from balance of Carbonate.
    (Carbonate disolved and goes down in history as the shortest lived Colorado County.)


    Feb 23 - Pitkin (Aspen) created from Gunnison

    Mar 4 - Dolores (Rico) created from Ouray.

    La Plata county seat moved to Durango.


    Grand county seat moved to Grand Lake.


    Feb 10 - Garfield (Carbonate) created from Summit.

    Feb 11 - Delta (Delta) created from Gunnison.

    Feb 11 - Eagle (Red Cliff) created from Summit.

    Feb 11 - Montrose (Montrose) created from Gunnison.

    Feb 14 - Mesa (Grand Junction) created from Gunnison.

    Feb 27 - Uncompaghre (Ouray) created by renaming Ouray

    Mar 2 - Ouray re-created by resinding the Feb 27 act.

    Mar 2 - San Miguel (Telluride) created from San Juan.

    Garfield county seat moved to Glenwood Springs.


    Apr 14 - Archuleta (Pagosa Springs) created from Conejos.


    Colorado Supreme Court rules North Park is in Larimer instead of Grand

    Custer county seat moved to Silver Cliff.


    Feb 9 - Washington (Akron) created from Weld.

    Feb 25 - Logan (Sterling) created from Weld.


    Grand county seat moved back to Hot Sulpher Springs

    Chaffe county seat moved to Buena Vista.


    Feb 19 - Morgan (Fort Morgan) created from Weld.

    Mar 15 - Yuma (Yuma) created from Washington.

    Mar 25 - Cheyenne (Cheyenne Wells) created from Elbert and Bent.

    Mar 25 - Otero (La Junta) created from Bent.

    Mar 25 - Rio Blanco (Meeker) created from Garfield.

    Mar 27 - Phillips (Holyoke) created from Logan.

    Apr   9 - Sedgwick (Julesburg) created from Logan.

    Apr 11 - Lincoln (Hugo) created from Elbert and Bent.

    Apr 11 - Kiowa (Sheridan Lake) created from Bent.

    Apr 11 - Kit Carson (Burlington) created from Elbert.

    Apr 11 - Prowers (Lamar) created from Bent.

    Apr 16 - Baca (Springfield) created from Las Animas.

    Apr 16 - Montezuma (Cortez) created from La Plata.


    Mar 27 - Mineral (Wason) created from Hinsdale, Rio Grande, and Saguache.

    Mineral county seat moved to Creede.


    Mar 23 - Teller (Cripple Creek) created from El Paso and Fremont.


    Mar 18 - Denver (Denver) created from Arapahoe.
    (Act later declared unconstitutional by Colorado Supreme Court.)

    Apr 15 - Adams (Brighton) created from Arapahoe.

    Apr 15 - Rest of Arapahoe renamed South Arapahoe (Littleton).


    Nov 4 - City and County of Denver created.

    Kiowa county seat moved to Eads.

    Yuma county seat moved to Wray.


    Apr 11 - South Arapahoe renamed Arapahoe.

    May 12 - Washington absorbed part of Adams and Arapahoe.

    May 12 - Yuma absorbed part of Adams and Arapahoe.


    Park absorbed south tip of Jefferson.


    May 5 - Jackson (Walden) created from Larimer.


    Feb 27 - Moffat (Craig) created from Routt.

    May 29 - Crowley (Ordway) created from Otero.


    Routt county seat moved to Steamboat Springs.


    Mar 8 - Alamosa (Alamosa) created from Costilla and Conejos.


    Eagle county seat moved to Eagle.


    Custer county seat moved to Westcliffe

    Chaffe county seat moved to Salida.


    Dolores county seat moved to Dove Creek.


    Nov 15 - City and County of Broomfield created from part of Adams, Boulder, Jefferson and Weld.

Dates from Colorado Post Offices 1859-1989 published by the Colorado Railroad Museum, 1990. Geographic information derived from The Historical Atlas of Colorado, by Thomas Noel, Paul Mahoney, and Richard Stevens. Pub. and copyright University of Oklahoma Press, 1994. This book contains great maps showing these divisions occuring as well as descriptive text about what lead to the divisions.

Return to Colorado Places by County.

This page was developed by Don Stanwyck.
It is currently maintained by Pauli Smith
Copyright 1998 & 2008, 2009 COGenWeb Project.