List of the largest counties in the United States by area

This is a list of the 100 largest counties in the United States by area. The list is based upon the total area of a county, both land and water surface, reported by the United States Census Bureau during the 2000 Census.^[1] Alaska is not divided into counties.

A different ranking becomes apparent when comparing county areas by land area alone as opposed to total area. Some counties, such as Keweenaw and Alger Counties in Michigan, include significant amounts of water in their total area and would not appear on a list that considered land area alone. This list also includes the four counties that would be included when water area is not included.

Nine US states are smaller than San Bernardino County, California, and two states, Rhode Island and Delaware are smaller than the smallest counties on this list.