The Union Pacific Big Springs Robbery was a robbery of a Union Pacific train near present-day Big Springs, Nebraska on September 18, 1877. The robbery was perpetrated by a gang of six outlaws led by Sam Bass. Though there were no fatalities, the bandits reportedly stole $60,000 in newly minted $20 gold pieces that was being shipped from the San Francisco Mint to a bank in the eastern United States, among other valuables. Contemporary press coverage of the sensational heist made Bass and his gang of "Black Hills Bandits" instantly famous. It remains the largest single robbery in the history of the Union Pacific Railroad. Several of the gang members were killed in the days following the robbery, but Bass escaped.