Cornelius Vanderbilt initially made his fortune in shipping. However, in the 1860's, he saw opportunity in the rapidly growing railroad industry. He took what had previously been a fragmented route, largely between NY and Chicago, and cleaned it up. Lines were connected, trains ran on one grand schedule as opposed to many small schedules, and he instituted standard procedures for all railways. This lowered costs and increased efficiency. When things are affordable and efficient, expansion becomes easier.