The World's Largest County: San Bernardino County, California

San Bernardino County, California is the largest county by land area in the United States—and the world.

• Area: 20,160 square miles (52,218 km²)
• Larger than: 9 U.S. states (including New Jersey, Connecticut, Delaware, Rhode Island)
• Geography: Spans from the Inland Empire suburbs across the Mojave Desert to the Nevada/Arizona borders.
• Population: ~2.2 million (2023), mostly concentrated in the southwestern valley.

Its vastness includes mountains, deserts, military bases (Fort Irwin, Marine Corps Logistics Base), and parts of Death Valley National Park. The county seat is San Bernardino city.