Formed May 1, 1803 (18th county)
Warren County (242,338), Lebanon (20,849), Mason (34,801)
The Modern dark red brick 1979 courthouse replaced an 1836 structure. It is on Justice Drive north of Cook Street. Ohio State Highway 48 is one block to the east of the structure. A. C. Voorhis & Associates are the building designers. A 1996 Justice Center and 2001 County Administration Building augment the courthouse in a complex of government buildings. Warren County was created on May 1, 1803 as the 18th county with Lebanon as the only county seat. It was taken from Hamilton County. It is named for Revolutionary War hero Joseph Warren. The county seat is named for the Biblical location.
Warren County government consists of an auditor, a sheriff, an attorney, and a coroner (executive). It has 3 Commissioners (legislative.) Seven Common Pleas Court Judges and a court clerk serve Warren County (judicial.) The county is in the southwest part of the state. Cincinnati, Ohio is directly southwest and Columbus, Ohio is northeast of the county. The county center is 3 miles East of Lebanon. The county is surrounded clockwise by Greene, Clinton, Clermont, Hamilton, Butler, and Montgomery counties.
The area of the county is 399.6 square miles. It is 82 out of 88 in the state. It ranks 10 out of 88 in population in the state. It has a density of 606.5 persons per square mile making it 11 out of 88 in the state. Warren County has 45.1% of its population in its incorporated areas. Interstate Highway 71 crosses northeast to southwest in the county from Clinton County to Hamilton County. Interstate Highway 75 enters from Montgomery County, north, and exits to Butler County, west. United States Highway 22 parallels Interstate Highway 71 from Clinton to Hamilton counties. United States Highway 42 comes from the north, Greene County, and goes to the west, Butler County. The county is a rectangle is an added horn sticking out of the northwest corner. Lebanon is located slightly west of center in the county. Mason is on the southwest border of the county. Lebanon is the county seat and Mason is the largest city. Lebanon is 8.6% of the county population while Mason is 14.4% of the county population. This county is in the Cincinnati-Middletown Metropolitan Statistical Area.
Butlerville
Corwin
Franklin
Harveysburg
Lebanon
Maineville
Mason
Morrow
Pleasant Plain
South Lebanon
Waynesville
Blanchester
Carlisle
Loveland
Middletown
Monroe
Springboro