Oberlin is a city in and the county seat of Decatur County, Kansas, United States. As of the 2010 census, the city population was 1,788.
On September 30, 1878, Northern Cheyenne fleeing from Indian Territory to their homes in the north, the Northern Cheyenne Exodus, attacked homesteaders near Oberlin, then a tiny hamlet. The Last Indian Raid in Kansas room in the Decatur County Museum and a monument in the town cemetery near the graves of the victims commemorate those depredations. Oberlin was platted as a town in 1878.
According to the United States Census Bureau, the city has a total area of 1.9 square miles (5.0 km²), all of it land.