Roodhouse is a city in Greene County, Illinois, United States. The population was 1,578 at the 2020 census. Roodhouse is located in n…Roodhouse is a city in Greene County, Illinois, United States. The population was 1,578 at the 2020 census. Roodhouse is located in northern Greene County at 39°28′55″N 90°22′18″W / 39.48194°N 90.37167°W. U.S. Route 67 passes through the center of the city, leading north 22 miles to Jacksonville and south 13 miles to Carrollton, the Greene County seat.