Monroe, Ohio Monroe, Ohio Monroe is a city located in east central Butler and west central Warren counties in the southwestern part of the U.S. state of Ohio. As of the 2010 Census, the city population was 12,442, up from 4,008 in 1990. Monroe was laid out in 1817 on the Dayton and Cincinnati pike. The city is named for President James Monroe, fifth President of the United States. In the early 1830s, Monroe contained one store and 119 inhabitants. Monroe is located at (39.444658, −84.364044). According to the United States Census Bureau, the city has a total area of , of
Monroe County, Michigan River Raisin National Battlefield Park. Monroe County was formed from the southern portion of Wayne County in 1817. At the time, the Michigan Territory, which had not yet received statehood, consisted of only Wayne County since Detroit was the only area with a population over 1,000 people. When the area became more populated, the southern portion of Wayne County was broken off to form Monroe County with the settlement of Frenchtown was platted with the name "Monroe". The settlement also incorporated as a village in 1817 and became the county seat of Monroe County. The county and its county seat