The U.S. government pitted two companies--the Union Pacific and the Central Pacific Railroads--against each other in a race for funding, encouraging speed over caution. Locomotives, rails, and spikes were shipped from the East through Panama or around South America to the West or lugged across the country to the Plains. In Ambrose's hands, this enterprise, with its huge expenditure of brainpower, muscle, and sweat, comes vibrantly to life.