Name of County
|
Date Formed
|
Boundary Changes
|
Parent County
|
Counties Created by Boundary Changes
|
Beaver
|
1866 Jan 10
|
Details
|
Iron, Millard
|
none
|
Box Elder
|
1856 Jan 05
|
Details
|
Utah Territory
|
none
|
Cache
|
1856 Jan 05
|
Details
|
Utah Territory
|
none
|
Carbon
|
1894 Mar 08
|
Details
|
Emery
|
none
|
Carson
|
1854 Jan 20
|
Details
|
Utah Territory
|
in Nevada Territory
|
Cedar
|
1856 Jan 05
|
Details
|
Utah
|
in Nevada Territory
|
Daggett
|
1919 Mar 04
|
Details
|
Uintah
|
none
|
Davis
|
1852 Mar 03
|
Details
|
Salt Lake
|
Morgan 1862
|
Deseret
|
1852 Mar 03
|
Details
|
Utah Territory
|
dissolved
|
Duchesne
|
1913 Mar 07
|
Details
|
Wasatch
|
none
|
Emery
|
1880 Feb 12
|
Details
|
Sanpete, Sevier
|
Carbon 1894, Grand 1890
|
Garfield
|
1882 Mar 09
|
Details
|
Iron, Sevier, Kane
|
none
|
Grand
|
1890 Mar 13
|
Details
|
Emery, Uintah
|
none
|
Greasewood
|
1855 dec 20
|
Details
|
Utah Territory
|
in Nevada Territory
|
Great Salt Lake
|
1850 Jan 31
|
Details
|
Utah Territory
|
renamed Salt Lake 1852
|
Green River
|
1852 Mar 03
|
Details
|
Salt Lake
|
shrank in Wyoming
|
Humboldt
|
1855 Dec 20
|
Details
|
Utah Territory
|
in Nevada Territory
|
Iron
|
1850 Jan 31
|
Details
|
Utah Territory
|
Garfield 1882
|
Juab
|
1850 Oct 05
|
Details
|
Utah Territory
|
Millard 1851
|
Kane
|
1864 Jan 16
|
Details
|
Washington, Utah Territory
|
Garfield 1882, San Juan 1880
|
Little Salt Lake
|
1850 Jan 31
|
Details
|
Utah Territory
|
dissolved
|
Millard
|
1851 Oct 04
|
Details
|
Juab
|
Beaver 1856
|
Morgan
|
1862 Jan 17
|
Details
|
Davis, Summit
|
none
|
Piute
|
1865 Jan 16
|
Details
|
Sevier
|
Wayne 1892
|
Rich
|
1868 Jan 29
|
Details
|
renamed from Richland
|
none
|
Richland
|
1864 Jan 16
|
Details
|
Utah Territory
|
renamed Rich 1868
|
Rio Virgin
|
1850 Oct 05
|
Details
|
Utah Territory
|
Arizona, Nevada Territories
|
Saint Marys
|
1855 Dec 20
|
Details
|
Utah Territory
|
Nevada Territory
|
Salt Lake
|
1852 Mar 03
|
Details
|
renamed from Great Salt Lake
|
Davis 1852, Summit 1854
|
Salt Lake Islands
|
1850 Jan 31
|
Details
|
Utah Territory
|
dissolved 1852 to Box Elder, Weber, Davis, Salt Lake, Tooele
|
San Juan
|
880 Feb 17
|
Details
|
Kane
|
none
|
Sanpete
|
1852 Mar 03
|
Details
|
Utah Territory
|
Emery 1880, Sevier 1865
|
Sevier
|
1865 Jan 16
|
Details
|
Sanpete
|
none
|
Shambip
|
1855 Dec 20
|
Details
|
Utah Territory
|
absorbed into Tooele, 1856
|
Shambro
|
1855 Dec 20
|
Details
|
Utah Territory
|
Nevada Territory
|
Summit
|
1854 Jan 13
|
Details
|
Salt Lake
|
Morgan 1862, Wasatch 1862
|
Tooele
|
1852 Mar 03
|
Details
|
Utah Territory
|
none
|
Uintah
|
1880 feb 18
|
Details
|
Wasatch
|
Daggett 1919, Grand 1890
|
Utah
|
1852 Mar 03
|
Details
|
Utah Territory
|
Cedar 1856
|
Wasatch
|
1862 Jan 17
|
Details
|
Summit
|
Duchesne 1913, Uintah 1880
|
Washington
|
1852 Mar 03
|
Details
|
Utah Territory
|
Kane 1864
|
Wayne
|
1892 Mar 10
|
Details
|
Piute
|
none
|
Weber
|
1852 Mar 03
|
Details
|
Utah Territory
|
none
|