Drawing of an attack by Native Americans on U.P.R.R. construction crew, 1868

The Union Pacific faced resistance from Native American tribes who were seeing treaties broken and their homelands invaded and irrevocably changed. The railroad workers were armed and oftentimes protected by U.S. Calvary and friendly Pawnee Indians, but the workforce routinely faced Native American raiding parties that attacked surveyors and workers, stole livestock and equipment, and pulled up track and derailed locomotives. https://americanhistory.si.edu/blog/TRR and https://exhibits.stanford.edu/rr/feature/native-americans-and-the-railroad