In June 1864, a flood destroyed the nearby Army camp called Camp Collins. When Lt. James Hannah and his men were looking for safer ground on which to relocate the camp, they encountered Mason, who suggested they relocate on land near his property. It was a two-story concrete
sutler's store built on the south edge of the camp, and Mason was appointed as the sutler, or store keeper for the camp. Mason and his partner, Mr. Sherwood, also supplied horses to the army camp. When the post office was located in the sutler's store, Mason was also appointed as the first postmaster to the camp. In 1877, President Hayes reappointed Mason as postmaster but Mason resigned the office in 1879. In 1868, Mason was instrumental in getting the county seat of Larimer County to Fort Collins from Laporte. Once the county seat was moved to Fort Collins, the courthouse was located on the second floor of the Old Grout sutler's store building. In 1871, Mason was elected Sheriff of Larimer County. He was reelected to the position in 1873. During his time as sheriff, Mason arrested noted criminal Happy Jack, but he subsequently escaped custody. In 1872, Mason purchased the Lindell flour mill from Elizabeth Auntie Stone and Henry C. Peterson. Joseph Mason donated 50 acres of land to help build
Colorado State University. Mason Street in Fort Collins is named for Joseph Mason. ==Personal life==