On March 24, 1803, the State of Ohio authorized the creation of Warren County. Residents named the county in honor of General Joseph Warren, a hero of the American Revolution. Many of the county's earliest settlers were members of various religious groups, including the Shakers and the Quakers.
Warren County is located in southwestern Ohio. The city of Cincinnati or its suburbs cover a portion of the county's four hundred square miles. The county's largest township is Deerfield Township, with a population of 25,515 people in 2000. Lebanon, the county seat, is the third largest urban area, with a population of 16,962 people in 2000. Warren County experienced tremendous growth between 1990 and 2000. Between 1995 and 2000, approximately seventeen thousand people moved to Warren County, increasing the county's population to 158,383 residents. The county averages 396 people per square mile.
Many Warren County residents work in Cincinnati. People finding employment in the county usually work in the sales, service, or manufacturing industries. A sizable tourist industry includes Paramount King's Island, the Ohio History Connection's Fort Ancient, and the Ohio Renaissance Festival. In 1999, the per capita income was 28,402 dollars, with 5.6 percent of the population living in poverty.
Most voters in Warren County claim to be independents.
Warren County was home to Ohio Governors Jeremiah Morrow and Thomas Corwin.