Texas continued to claim sovereignty over Greer County during and after the Civil War. It opened the land to veterans of the Texas Revolution and Confederate Army veterans and leased land to ranchers. In 1884, President Chester A. Arthur took a more active role in looking for a resolution of the dispute. However, the attempt failed to resolve anything. Meanwhile, area residents officially organized Greer County as a Texas entity in 1886, designating Mangum as the county seat. In 1890, Congress passed the Oklahoma Organic Act, which required the United States attorney general to resolve the boundary issue by filing suit against Texas.