Utah's 20 largest counties, ranked.

Salt Lake County holds more than a third of the state's people on the valley floor between the Wasatch and the Oquirrh ranges. Salt Lake City is the seat and the largest city, and Intermountain Health, the University of Utah, and the state government are among its biggest employers. That size is exactly why the county is the state's center of jobs, hospitals, and the airport.

Utah County runs along the west side of the Wasatch Range around Utah Lake, with Provo as the seat and the largest city. BYU and Utah Valley University anchor an economy that has made the county the clear number two in the state by population. Its growth since the 2020 census is among the fastest on this list, and the new building shows along the whole valley floor.

Davis County is the narrow strip between the Wasatch Range and the Great Salt Lake, squeezed between Salt Lake and Weber counties. Layton is the largest city and Farmington the seat, with Hill Air Force Base a major employer and Antelope Island State Park just offshore. With mountains on one side and water on the other, almost every piece of private land is either built on or farmed.

Weber County centers on Ogden, where the Weber River leaves the mountains for the valley floor, and Ogden is both the seat and the largest city. Weber State and the county's share of the region's ski resorts, including Snowbasin and Powder Mountain, sit within its borders. Ranked fourth by population, it anchors the north end of the Wasatch Front's continuous metro corridor.

Washington County fills the low-desert southwest corner of the state, with St. George as the seat and the largest city. Zion National Park is a short drive from town, and Snow Canyon, Sand Hollow, Quail Creek, and Gunlock state parks spread through the country around it. The county has grown by close to a fifth since the 2020 census, the second-fastest rate on this list.

Cache County fills a high mountain valley in the north of the state, with Logan as the seat and the largest city. Utah State University anchors the town, and Beaver Mountain and Cherry Peak sit in the mountains around the valley. Ranked sixth, the county has cold winters and some of the strongest winter inversions in the state, a real part of the decision to live here.

Tooele County is the wide basin west of the Oquirrh Mountains, with Tooele City as the seat and the largest town. It has grown faster than any other county on this list since the 2020 census, and most of its land is federal, which keeps new housing crowded into the valley around town. There is no ski resort and no state park inside the county, so the growth is about the land and the room.

Iron County sits in a high mountain valley in Southern Utah, with Cedar City as the largest city and Parowan as the seat. Southern Utah University anchors Cedar City, Brian Head rises above the valley for skiing, and Cedar Breaks National Monument sits up on the plateau to the east. The county has grown faster than most on this list since the 2020 census, and its elevation is why winters here bring real snow.

Box Elder County runs from the shore of the Great Salt Lake north toward Idaho, with Brigham City as the seat and the largest town. The county sits below the Wellsville Mountains and holds Golden Spike National Historical Park out on the lake's northern reach, with Willard Bay State Park at its southern end. It has grown faster than most counties on this list since the 2020 census.

Summit County is the high mountain country east of the Wasatch crest, with Park City as its largest town and Coalville as the seat. Park City Mountain and Deer Valley put two major ski areas inside the county, and Rockport and Echo state parks sit within its borders. It ranks near the bottom of this list by population but at the very top by median home value, a sign of how much of the county is ski country and resort ground.

Wasatch County lies on the east side of the range from Park City, with Heber City as the seat and the largest town. Jordanelle, Deer Creek, and Wasatch Mountain state parks ring the valley, and while no ski resort sits inside the county, the Park City resorts lie just over the divide. Its growth since the 2020 census has been faster than the Wasatch Front's core counties, much of it clustered around Heber City and the reservoirs at the valley's edge.

Uintah County is the high-desert Uinta Basin in eastern Utah, with Vernal as the seat and the largest city. Dinosaur National Monument sits in the county near the town of Jensen, and Steinaker and Red Fleet state parks hold the area's reservoir recreation. Ranked twelfth, the county keeps most of its people in Vernal while the surrounding ground stays open and mostly federal.

Sanpete County is a high valley in central Utah, with Ephraim as the largest town and Manti as the seat. Snow College anchors Ephraim, and Palisade State Park sits in the hills at the valley's edge, with Yuba Reservoir shared with the county to the west. It ranks thirteenth, and most of its people live in the string of towns along the valley floor.

Sevier County is the valley along the Sevier River in central Utah, with Richfield as the seat and the largest town. Fremont Indian State Park lies in the hills west of the valley, and the county sits just east of where I-70 and I-15 meet at Cove Fort. Richfield works as the supply town for a wide stretch of central Utah, which is what its rank among the smaller counties here means in practice.

Duchesne County makes up much of the Uinta Basin's lower country in eastern Utah, with Roosevelt as its largest town and the small city of Duchesne as the seat. Starvation Reservoir State Park sits within the county, and the county's growth since the 2020 census has been steady. It ranks fifteenth, and its people live mostly in Roosevelt, Duchesne City, and the smaller towns between them.

Carbon County runs down the Castle Valley corridor in eastern Utah, with Price as the seat and the largest town. Utah State University Eastern anchors Price, and Scofield Reservoir State Park sits in the mountains at the county's edge. The county is among the slowest growers on this list, which is part of why its towns have not seen the building boom the counties closer to the Wasatch Front have.

San Juan County stretches across the canyon country of southeastern Utah, with Blanding as its largest town and Monticello as the seat. It holds the Needles district of Canyonlands, Natural Bridges, Hovenweep, and Bears Ears, along with the Edge of the Cedars and Goosenecks state parks. The county ranks seventeenth and has barely grown since the 2020 census.

Millard County is the long Pahvant Valley in central Utah, with Delta as its largest town and Fillmore as the seat. I-15 runs the length of the county, and I-70 begins at Cove Fort at its eastern end, with Territorial Statehouse State Park in Fillmore. It ranks eighteenth, and its towns string out along the valley and the freeway.

Juab County is the valley running south from Utah County along I-15, with Nephi as the seat and the largest town. Little Sahara Recreation Area and Yuba State Park both lie within the county, and US-6 branches east from Nephi toward the high country. It ranks nineteenth, and its growth since the 2020 census has been one of the fastest rates on this list.

Morgan County is a narrow mountain valley on the Weber River, with Morgan as the seat and the largest town. East Canyon and Lost Creek state parks sit in the hills around the valley, and its winters bring heavy snow. It ranks twentieth, the smallest county on this list by population, and it stays quiet even though it borders the Ogden area.