There were reasons for this marked shift of national emphasis from political affairs to the great development of the nation's economy and industry. The nation at large was exhausted from the Civil War. By the 1870's, most Americans felt that it was time to turn to building their own lives. At the same time, the post-war expansion of railroad transportation, and the exploitation of steam and electrical power obviously played major roles. Equally important too, was the vast physical size of the nation itself with its endless supply of resources—iron, coal copper, gold, etc. Almost all these lay waiting after the war, inviting exploitation.