Casper was established in the early summer of 1888, and was named after Fort Caspar, a military post first established in 1858. The site of Fort Caspar was called Camp Platte from 1840 to 1847. When the Mormons passed through here in June 1847, they built and operated a ferry across the river, and then the name was changed to Mormon Ferry or Mormon Crossing. Louis Guinard built a bridge across the river  at this point in the winter of 1858-59, and the name was then changed to Platte Bridge Station. Lieutenant Caspar W. Collins was killed by Indians near the fort on July 26, 1865, and in October of that year Major General Pope ordered the name changed to Fort Caspar.

Source: Annals 15 (1)