The 25 Largest US Counties by Area
The largest county in the United States is San Bernardino County, California, covering 20,057 square miles — larger than the states of New Jersey, Connecticut, Delaware, and Rhode Island combined.
Most of the largest US counties are in Alaska and the western states, where sparse population and vast public lands result in enormous administrative areas. The Bureau of Land Management manages much of the federal land in these counties.
Top 25 largest counties by area
Note: the data below shows state-level area, not individual county area. For county-level detail, use our interactive county map and hover any county for its full stats.
Why are western counties so large?
When western territories were organized in the 19th century, the population was extremely sparse. Counties were drawn to cover entire regions that might contain only a few hundred residents. As population grew along the coasts and in river valleys, eastern counties were subdivided further — but western counties largely kept their original boundaries.
Alaska's Yukon-Koyukuk Census Area alone is larger than Montana — yet it has fewer than 5,500 residents.
Large counties vs. small counties
To put county size in perspective, here's how the extremes compare:
- Largest: San Bernardino County, CA — 20,057 sq mi
- Smallest: Kalawao County, HI — 12 sq mi (a former leper colony on Molokai)
- Most populated: Los Angeles County, CA — ~9.8 million people
- Least populated: Loving County, TX — ~64 people
Explore county data
- US County Map — choropleth of all 3,143 counties by population, income, age, and more
- County Map with Cities — explore any county with city markers and population data
- What County Am I In? — find your county by GPS or address
- Map Area Calculator — draw any shape and measure its area in sq mi, km, or acres
- Blank Map of the US — free downloadable map with county boundaries