County size comparison

Worked example: San Bernardino County against the states

The 2024 Gazetteer lists 20,068 square miles of land for San Bernardino County. Summing each state's counties gives these states less land: District of Columbia, Rhode Island, Delaware, Connecticut, Hawaii, New Jersey, Massachusetts, New Hampshire, Vermont, Maryland.

The largest county-equivalent overall is Yukon-Koyukuk, Alaska, at 145,769 square miles, which is 7.3 times San Bernardino.

Why the outline keeps its true size

Web maps use Web Mercator, which enlarges shapes as they move away from the equator. Drag a county north on a Mercator map by simply shifting its coordinates and it would appear to grow. This tool instead moves every vertex across the sphere: it keeps each vertex's distance and bearing from the shape's center and rebuilds the outline around the new center. The outline then stretches on screen exactly as the underlying map does, so the comparison stays honest.

The land areas in the readout come from the Census Gazetteer, not from measuring the drawn outline, so they are exact to the published figure.

Land area versus total area

Gazetteer land area excludes lakes, bays, and coastal water inside the boundary. Counties on the Great Lakes or with large reservoirs have much more total area than land area. State totals on this page are the sum of their counties' land area, which adds up to 3,533,469 square miles for the 50 states and DC.

How to use it

Choose the county to move in the first box. Choose a state to compare in the second; it is drawn in gray at its real location and the county outline is placed over it. Click anywhere on the map to move the county there. The readout gives both land areas, the ratio, and the number of states with less land than the county.

The outline you move comes from the same Census 2024 cartographic boundary file the county finder uses, simplified for the web, so tiny islands and inlets may be smoothed away. That affects the drawing only; the land area in the readout is the published Gazetteer value.

Counties larger than whole states

Rhode Island has 1,034 square miles of land. By that yardstick 640 county-equivalents are larger than a whole state. Against Delaware's 1,949 square miles the count is 292, and against Connecticut's 4,842 it is 84.

Of the 50 largest, 18 are in Alaska and 31 are in the 11 Census West states outside Alaska and Hawaii. The largest counties ranking lists the top 50 and a separate top list outside Alaska. For the other end of the scale, the smallest county-equivalents are independent cities of a few square miles, listed in the smallest counties ranking.