1883 Lewiston Post Office was established on January 29, 1883 in Sweetwater County prior to the formation of Fremont County. Lewiston was named for a man by the name of Lewis who erected a stamp mill and hoisting works on gold properties discovered by Captain H. G. Nickerson in 1882. Lewiston had a newspaper titled Lewiston Gold Miner.
1884 Phillips Post Office was established on January 29, 1884 with John H. Phillips as postmaster.
1914 Big Creek Post Office was established on January 29, 1914 with Harry A. Hunter as its postmaster. Big Creek was originally located on Big Creek at the Big Creek Ranch.
1964 Sheridan Inn was designated a National Historic Landmark.