The 10 Largest Counties in the U.S.

In the United States, the term “county” represents an administrative subdivision of a state, with clearly drawn boundaries. Most counties have a county seat where their administrative functions are centered. Of the 50 individual states that make up the United States, 48 of them use the term ‘county.’ Two states, Alaska and Louisiana are not divided into counties. Instead, Alaska uses the terms “borough” and “census areas” while Louisiana uses “parishes” to describe its administrative areas.

Most importantly, there are 3,144 counties in the U.S., and the areas of each county vary widely between the states. The largest counties in the United States by total area (both land and water surface areas) are all situated in the western part of the country. These are the only counties with total land and water surface area of more than 10,000 square miles. This means each of them is larger than the entire state of Vermont at 9,620 miles! 

However, note that Alaska and Louisiana do not have counties, therefore are not included in this list. If included with the remainder of the counties in the U.S., Alaska’s boroughs and census areas would easily top the list because they’re larger than all the counties in the United States. 

Below is a list of the 10 largest counties in the United States by area, ranked from lowest to highest as reported by the United States Census Bureau.

10 Largest Counties In The U.S

10. Harney County, Oregon (10,226 square miles)

At 10,226 square miles of total land and water surface area, Harney County is the tenth-largest county in the United States and the largest in Oregon. It is, in fact, larger in area than six U.S. States combined! Harney County was named in honor of William S. Barney, a popular military officer in 1889. The population of Harney County was 7,495 in 2020, making it the sixth-least populous county in Oregon. The county seat is in Burns and it is the tenth of the only 10 counties in the U.S. with more than 10,000 square miles of area (excluding boroughs and census areas in Alaska).

9. Inyo County, California (10,192 square miles)

With a total land and water surface area of 10,192 square miles, Inyo County is the ninth-largest county by area in the U.S. and the second-largest in California, after San Bernardino County. According to the 2020 census, the county has a population of 19,016, predominantly Whites. The county seat is in Independence. Notable attractions in Inyo County are Mushroom Rock, Mount Whitney, and Death Valley National Park.

8. Sweetwater County, Wyoming (10,491 square miles)

The eighth-largest county in the United States, Sweetwater County has a total land and water surface area of 10,491 square miles –larger than six individual states put together! As of the 2020 United States Census, the population was 42,272, making it the fourth-most populous county in Wyoming. Its county seat is Green River and it was named after the Sweetwater River, which is a part of the Mississippi River system. Sweetwater County comprises the Green River, Rock Springs, and the Wyoming Micropolitan Statistical Area. 

7. Lincoln County, Nevada (10,637 square miles)

While only the third-largest county by area in the state of Nevada, it is the seventh-largest county by area in the United States, with total land and water surface area of 10,637 square miles. Located in the U.S. state of Nevada, Lincoln County is dry and sparsely populated. As of the 2018 census, the population was only about 5,201. It is named after President Lincoln and the country seat is Pioche Template. Lincoln County is notable for being home to the Area 51 Air Force base. There are 16 official wilderness areas in Lincoln County alone, as well as Pahranagat National Wildlife Refuge and parts of Desert National Wildlife Refuge and Humboldt National Forest. 

6. Apache County, Arizona (11,218 square miles)

Shaped in a long rectangle running from north to south, Apache County is located in the northeast corner of Arizona. Apache County has a total land and water surface area of 11,218 square miles making it the sixth-largest county by area in the United States and the third-largest in Arizona. It has a population of 71,818 people and the county seat is St. Johns. The Navajo Nation and the Fort Apache Indian Reservation are federally recognized tribes that occupy a major part of the county. It also contains part of Petrified Forest National Park, while Canyon de Chelly National Monument is entirely within the county.

5. Mohave County, Arizona (13,461 square miles) 

This is the fifth-largest county in the United States, with a total land and water surface area of 13,461 square miles. Located in the northwestern part of Arizona, Mohave County contains the Kaibab, Fort Mojave, and Hualapai Indian Reservations. Its county seat is Kingman. As of the 2020 census, the population of Mohave County was 213,267 and its largest city is Lake Havasu City. This country also contains parts of Grand Canyon National Park and Lake Mead National Recreation Area and all of the Grand Canyon–Parashant National Monument. It is also notable for being home to the large Church of Jesus Christ of Latter-Day Saints.

4. Elko County, Nevada (17,203 square miles)

Established from Lander County in 1869, Elko County was named after the county seat of Elko. With a total land and water surface area of 17,203 square miles, it is the fourth-largest county by area in the United States. As of the 2019 census, it had a population of 52,778 people, made up of largely European Americans, Latinos, Hispanics, and First Nation Americans. The county is in the Pacific Time Zone, though few communities such as Mountain City, Owyhee, Jackpot, and Jarbidge observe the Mountain Time Zone due to their economic relations with the neighboring state of Idaho.

3. Nye County, Nevada (18,159 Square miles)

At 18,159 square miles of land and water area, Nye County is Nevada’s largest county by area and the third-largest county in the United States. This country was named after James W. Nye, the first Governor of the Nevada Territory. Nye County’s land area is larger than that of Maryland, Hawaii, Vermont, and New Hampshire, and larger than the combined area of Massachusetts, Rhode Island, New Jersey, and Delaware. As of the 2019 census, the population was 46,523. The county seat in Tonopah is where about 86% of the county’s population resides. The major tourist attractions in Nye County are the Nevada Test Site, the Grand Canyon, the National Wildlife Refuge, the White River Valley, the Ash Meadows, and the Great Basin Sky Islands.

2. Coconino County, Arizona (18,661 square miles)

Coconino County in Arizona has a total area of 18,661 square miles of which 18,619 square miles are land and 43 square miles (0.2%) are covered by water. It is the second-largest county by area in the United States and the largest in Arizona. It has more land area than nine U.S. states! Its county seat is Flagstaff and the population of 143,476 people in Coconino County constitutes mostly federally designated Indian reservations, second in scale only to Apache County. The reservations are the Navajo, Hualapai, Hopi, Havasupai, and Kaibab. Coconino County is well-known for the Flagstaff metropolitan statistical area and the Grand Canyon National Park. 

1. San Bernardino County, California (20,105 square miles)

San Bernardino County in California is the largest county in the United States by area with a total surface area of 20,105 square miles! It is also the largest county in California and is larger than 9 U.S. states combined —this is close to the size of the state of West Virginia and is also slightly larger than the nation of Switzerland in square miles! This vast county is part of the Inland Empire region, spanning an area from south of the San Bernardino Mountains to the Nevada border and the Colorado River. As of 2020, over 2 million people lived in San Bernardino County, making it the fifth-largest county in terms of population. With 53.7% of them being Hispanics, it is considered California’s most populous majority-Hispanic county and the second-largest nationwide. There are at least 35 official wilderness areas in San Bernardino County, the largest number of any county in the United States.

What is the Smallest County in the U.S.?

When learning about the largest counties in the United States, it’s interesting to take a look at the opposite side of the spectrum in order to grasp just how big places like San Bernadino and Mohave County truly are. The smallest county in the U.S. is Alexandria, Virginia, which covers a mere 15.35 sq mi of territory. Despite its relatively tiny surface area, Alexandria boasts a healthy population of some 150,00+ citizens.

Summary Of The 10 Largest Counties In The U.S

Honorable Mention:

In case you are curious, here are five more of America’s largest counties. Would you believe that you have to go down to #39 on the list to find one from Texas?

11. Navajo County, Arizona, 9,959 square miles, County Seat – Holbrook

12. Malheur County, Oregon, 9,930 square miles, County Seat – Vale

13. Humboldt County, Nevada, 9,658 square miles, County Seat – Winnemucca

14. Fremont County, Wyoming, 9,266 square miles, County Seat – Lander

15. Maricopa County, Arizona, 9,224 square miles, County Seat – Phoenix

If you go by population instead of area, the largest counties are:

1. Los Angeles County, California – 9,721,138
2. Cook County (Chicago), Illinois – 5,109,292
3. Harris County (Houston), Texas – 4,780,913
4. Maricopa County (Phoenix), Arizona – 4,551,54
5. San Diego County, California – 3.276,208

The photo featured at the top of this post is © Dominic Gentilcore PhD/Shutterstock.com