The Platte River Valley served as America’s great road west, providing a natural pathway for westward expansion across the continent during the nineteenth century. The Oregon Trail followed the South Platte River along much the same route as the highway, and beginning in 1841, nearly 250,000 travelers crossed the plains to Oregon and California over this important overland route. At O'Fallon's Bluffs, wagon trains faced one of the most difficult and dangerous spots on the trail, where the Platte River cut directly against the bluff and forced travel onto a narrow roadway; deep sand trapped wagon wheels, and Indian attacks were always a danger. Ruts made by thousands of wagon wheels still remain. Though first traveled primarily by immigrants, the trail was later used by the Pony Express and became an important freight and military route. After the trans-continental railroad across Nebraska was completed in 1867, travel on the trail declined, but the Great Platte Valley route remained an important modern thoroughfare across Nebraska and the nation.