Wyoming is a city in Stark County, Illinois, United States. The population was 1,429 at the 2010 census, up from 1,424 in 2000. It is the headq…Wyoming is a city in Stark County, Illinois, United States. The population was 1,429 at the 2010 census, up from 1,424 in 2000. It is the headquarters of the Rock Island Trail State Park. Wyoming is part of the Peoria, Illinois Metropolitan Statistical Area. The former CB&Q Railroad depot in town is the Rock Island Trail State Park's headquarters.