Sculptor Avard Fairbanks's statue at the National Historic Trails Interpretive Center in Casper, Wyoming, depicting the changeover of Pony Express riders. Casper is roughly midway on the horse-borne mail route that ran between St. Joseph, Missouri, and Sacramento, California. Three other trails besides the Pony Express route -- the Oregon, Mormon, and California trails -- passed through or near present-day Casper. Photo by Carol Highsmith, 2015.