While AMC's Hell on Wheels is historical fiction, "Hell on Wheels" encampments were a real-life part of America's westward expansion. One of the earliest known appearances of the term "Hell on Wheels" comes from newspaperman Samuel Bowles, who used the phrase to describe the collection of gambling houses, dance halls, saloons, and brothels housed in flimsy canvas tents that accompanied the Union Pacific railroad workers westward.

Curious to see the real railroad workers' encampments from the 1860s? Click through this gallery of archival photos provided by the University of Iowa's Levi Leonard Libraries.

To see more artifacts from the era, check out the University of Iowa Libraries Levi Leonard Papers.