Approximately 800 square miles.
Shelby County, TN is 784 sq mi (2,031 km²).
Jackson county is 100.6 square miles
Onondaga County, NY is 806 square miles.
Marquette County, Michigan is 3,425 square miles.
Darlington County, SC is 567 square miles.
Hennepin County, Minnesota is 606 square miles.
Rockwall County: 129 square miles.
Lincoln County is 4 831 square miles.
Tillamook County, Oregon is 1,133 square miles.
Fulton County, GA's area is 534.75 square miles.
Baldwin County, AL's area is 2,027 square miles.