| County | FIPS Code | County Seat | Established in | Population | Area (sq mi) | Area (km2) |
|---|---|---|---|---|---|---|
| Beaver County | 1 | Beaver | January 5, 1856 | 6,710 | 2,590 | 6,708 |
| Box Elder County | 3 | Brigham City | January 5, 1856 | 56,046 | 5,746 | 14,882 |
| Cache County | 5 | Logan | January 5, 1857 | 128,289 | 1,165 | 3,017 |
| Carbon County | 7 | Price | March 8, 1894 | 20,463 | 1,478 | 3,828 |
| Daggett County | 9 | Manila | January 7, 1918 | 950 | 697 | 1,805 |
| Davis County | 11 | Farmington | October 5, 1850 | 355,481 | 299 | 774 |
| Duchesne County | 13 | Duchesne | January 4, 1915 | 19,938 | 3,241 | 8,394 |
| Emery County | 15 | Castle Dale | February 12, 1880 | 10,012 | 4,462 | 11,557 |
| Garfield County | 17 | Panguitch | March 9, 1882 | 5,051 | 5,175 | 13,403 |
| Grand County | 19 | Moab | March 13, 1890 | 9,754 | 3,672 | 9,510 |
| Iron County | 21 | Parowan | January 31, 1850 | 54,839 | 3,297 | 8,539 |
| Juab County | 23 | Nephi | March 3, 1852 | 12,017 | 3,392 | 8,785 |
| Kane County | 25 | Kanab | January 16, 1864 | 7,886 | 3,990 | 10,334 |
| Millard County | 27 | Fillmore | October 4, 1851 | 13,188 | 6,572 | 17,021 |
| Morgan County | 29 | Morgan | January 17, 1862 | 12,124 | 609 | 1,577 |
| Piute County | 31 | Junction | January 16, 1865 | 1,479 | 758 | 1,963 |
| Rich County | 33 | Randolph | January 16, 1864 | 2,483 | 1,029 | 2,665 |
| Salt Lake County | 35 | Salt Lake City | January 31, 1850 | 1,160,437 | 742 | 1,922 |
| San Juan County | 37 | Monticello | February 17, 1880 | 15,308 | 7,820 | 20,254 |
| Sanpete County | 39 | Manti | January 31, 1850 | 30,939 | 1,590 | 4,118 |
| Sevier County | 41 | Richfield | January 16, 1865 | 21,620 | 1,911 | 4,949 |
| Summit County | 43 | Coalville | January 13, 1854 | 42,145 | 1,872 | 4,848 |
| Tooele County | 45 | Tooele | January 31, 1850 | 72,259 | 6,941 | 17,977 |
| Uintah County | 47 | Vernal | February 18, 1880 | 35,734 | 4,480 | 11,603 |
| Utah County | 49 | Provo | January 31, 1850 | 636,235 | 2,003 | 5,188 |
| Wasatch County | 51 | Heber City | January 17, 1862 | 23,530 | 1,176 | 3,046 |
| Washington County | 53 | St. George | March 3, 1852 | 177,556 | 2,426 | 6,283 |
| Wayne County | 55 | Loa | March 10, 1892 | 2,711 | 2,461 | 6,374 |
| Weber County | 57 | Ogden | January 31, 1850 | 260,213 | 576 | 1,492 |
