What caused the building of the Transcontinental Railroad to be delayed

The First Continental Railroad was a continuous railroad line constructed in the decade of 1860. It connected the city of Omaha in Nebraska with Sacramento in California. It was delayed because it trespassed Native American territories and that was seen by the Native American as a violation of the treaties that they had with the United States. The Native American people responded to this violation attacking the workers, while the Union Pacific, which was the company building the railroad, increase their security.