Oklahoma is a borough in Westmoreland County, Pennsylvania, United States. The population was 809 at the time of the 2010 census. Oklahoma is located at 40°34′54″N 79°34′29″W / 40.58167°N 79.57472°W. According to the United States Census Bureau, the borough has a total area of 0.8 square miles, of which 0.7 square miles is land and 0.04 square mile…Oklahoma is a borough in Westmoreland County, Pennsylvania, United States. The population was 809 at the time of the 2010 census. Oklahoma is located at 40°34′54″N 79°34′29″W / 40.58167°N 79.57472°W. According to the United States Census Bureau, the borough has a total area of 0.8 square miles, of which 0.7 square miles is land and 0.04 square miles is water.