what county is new castle colorado in
Location in Garfield County and the state of Colorado. Coordinates: 39Â°34â²20â³N 107Â°32â²6â³W / 39.57222Â°N 107.53500Â°W / 39.57222; -107.53500Coordinates: 39Â°34â²20â³N 107Â°32â²6â³W / 39.57222Â°N 107.53500Â°W / 39.57222; -107.53500. The Town of New Castle is a Home Rule Municipality in Garfield County, Colorado, United States. The population was 1,984 at the 2000 census.