Ashcroft is an extinct mining town located in Pitkin County, Colorado, United States. The silver mining camp was founded as Castle Forks City in the spring of 1880. A post office named Ashcroft operated at the site from August 12, 1880, until August 5, 1881, when the name was changed to Chloride. The Chloride post office operated until January 3, 1882 wh…Ashcroft is an extinct mining town located in Pitkin County, Colorado, United States. The silver mining camp was founded as Castle Forks City in the spring of 1880. A post office named Ashcroft operated at the site from August 12, 1880, until August 5, 1881, when the name was changed to Chloride. The Chloride post office operated until January 3, 1882 when the name was changed back to Ashcroft. The renamed Ashcroft post office finally closed on November 30, 1912.