Cortland is a city in Trumbull County, Ohio, United States located on the eastern shore of Mosquito Creek Reservoir. Walnut Run is the creek that runs through town. The population was 6,830 at the 2000 census. Cortland became a village in 1874 with the construction of a railroad depot. It became a city in 1980 when its population exceeded 5,000 people. Cortland apartments for rent comparison page shows most up to date rent information on Cortland apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.