Largest Counties in the US by Area (and Population)

San Bernardino County, California is the largest county in the United States, with 20,068 square miles (51,977 km²) of land. That is the answer if "county" means a county. If you include county equivalents, the nine largest are all in Alaska, led by the Yukon-Koyukuk Census Area at 145,768 square miles of land, which is larger than every state except Alaska, Texas and California.

San Bernardino County stretches from the suburbs east of Los Angeles across the Mojave Desert to the Colorado River at the Nevada and Arizona lines. It is larger by land area than 9 states: Connecticut, Delaware, Hawaii, Maryland, Massachusetts, New Hampshire, New Jersey, Rhode Island, Vermont. It also has 2,224,091 residents (July 2025), more than 15 states.

Ranked by land area in the Census Bureau's 2026 Gazetteer. Population is the July 1, 2025 estimate (Vintage 2025).

The list mixes two very different kinds of unit. Alaska's boroughs and census areas are huge because the state has few people spread over a vast area; Yukon-Koyukuk has about 5,028 residents, roughly one person per 29 square miles. The lower-48 counties on the list are all in the desert Southwest, in California, Arizona and Nevada, where large stretches of desert and mountains have few residents.

Leaving out Alaska and Hawaii, the ten largest counties by land area are all in the West:

Coconino County, Arizona (Flagstaff and the Grand Canyon's South Rim) is second. Nye and Elko in Nevada come next. You can browse these on the Arizona county list and the Nevada county list, or see San Bernardino in context on the California county map.

The biggest county or county equivalent by land area in every state, with its share of the state's land:

Where a state has few counties, one of them can take up a large part of it. In Delaware, Sussex County covers 48% of the state, and in Hawaii, Hawaii County (the Big Island) covers 63%.

Alaska has no counties. It has 19 organized boroughs, which are county-like governments, and one huge Unorganized Borough that has no regional government at all. For statistics the Census Bureau divides the Unorganized Borough into 11 census areas. Together they make Alaska's 30 county equivalents, which share 571,409 square miles of land, an average of 19,047 square miles each.

Whether those count as "counties" depends on the question. For Census statistics, they are county equivalents and appear in every county-level table. For local government, only the boroughs are governments. That is why many lists of the largest counties quietly start with San Bernardino: they rank only true counties, or only the lower 48. The Alaska borough and census area map shows how the units fit together.

The smallest county equivalents are Virginia's independent cities. Falls Church city covers just 2.0 square miles of land, followed by Lexington city (2.5) and Manassas Park city (3.0).

Among units that are not independent cities, the smallest are:

Kalawao County, Hawaii is the smallest true county by area (12.0 sq mi) and the second least populous (82 residents). New York County, which is Manhattan, is second smallest by area and has 1,664,862 people on 22.7 square miles. The median county or equivalent covers 616 square miles of land.

Los Angeles County is the most populous county by a wide margin, with 9,694,934 residents on July 1, 2025, more than 40 of the 50 states. Cook County, Illinois (Chicago) and Harris County, Texas (Houston) are next, each above 5 million.

The least populous county is Loving County, Texas, with an estimated 52 residents, followed by Kalawao County, Hawaii (82) and King County, Texas (192).

Many lists rank counties by total area, which includes lakes, reservoirs and coastal water. That changes the order where water is significant: Great Lakes counties in Michigan and Wisconsin, and coastal counties in Alaska and Florida, carry large water areas that are not land anyone could stand on. This article ranks by land area because that is what most people mean by size. San Bernardino County has only 37 square miles of water, so its total area (20,106 sq mi) is close to its land figure either way.

Older lists also use 2000 or 2010 Census measurements and still show Valdez-Cordova Census Area, which was split into Chugach and Copper River census areas in 2019. To explore county sizes yourself, the interactive US county map draws every county from generalized Census boundaries, and how many counties are in the US lists each state's count.