The United States Geological Survey says there are 3,141 counties and county equivalents in the 50
States and the District of Columbia. They range in size from (excluding Alaska census areas) the western giants, San Bernie CA, Coconino AZ and Nye and Elko in Nevada to the eastern New York County (Manhattan) at 22.83 square miles, Bronx at 42.10 square miles and the tiniest, Kalawao Hawaii at 11.99.
Here they all are via Econbrowser's "The geography of success":
I'm not exactly sure what it means but there seem to be definite regional patterns.
HT: Abnormal Returns