A flight from New York to San Francisco can be an all day affair including having to deal with security and checking in at the airport. Consider, however, that same trip in 1800. How long would it take to travel that distance over land?
The 1932 Atlas of the Historical Geography of the United States included some nifty maps showing the travel time from New York City in 1800 and several dates afterwards.
You can definitely "see" railroads being put down as time goes on- as well as identify where mountain ranges make travel more difficult.