Afton Wyoming lies at the south end of Star Valley between the Peaks of the Salt River Range in western Wyoming and the Webster Range of eastern Idaho. Afton is the largest town in Star Valley. Just a few miles east of Afton you will find the worlds largest intermittent spring one of nature's wonders, it is also called periodic spring. Aftons Population (year 2000): 1,818 Males: 863 (47.5%), Females: 955 (52.5%) Afton is the home of the Lincoln County Fair.