People had only been living in the US for 150 years when we gained our independence. Most people living in the US were for a long time on the east coast as it was still quite difficult to travel from place to place. Roads had just started being established, and traveling by horse or even by foot could take a very long time. One of the first trips west was organized by the President Thomas Jefferson. From 1804 to 1806 he sent the explorers Lewis & Clark on a strategic mission. We had recently purchased the territory of Louisiana, and wanted to assess the purchase. The main goals were to attempt to find a water passage between the Atlantic and the Pacific to be able to trade with Asia more easily. Another purpose was to ensure the Native Americans were aware of the soverignty of the US over them. Although a direct route was never found, this give an idea to how much time it can take someone to travel across the country. However, with the development of the locomotive in the 1880s, it became easier to travel from east to west.
Up until 1915, most people could not afford the luxury of traveling, and did not travel domestically for vacation. With the development of the automobile, Ford for example started marketing to the lower income population, explaining a car was easier to maintain than a hose, but cars were not affordable for the average American until 1913 when Ford dropped their prices. Although the automobile was finally available, we did not yet have a well-developed road system. We additionally had to deal with World War I and II, Prohibition from 1919-1933, and the fall of the stock market (bourse) in 1929. After the recovery of our economy we finally see a push for development of tourism and hotels in Florida as we think of them today. It was at this time many hotels were built in Miami in the style of Art Deco, a tourist attraction to this day. Florida remains a large tourist attraction, and additionally has added parks like Disney and Universal Studios, and more recently the Harry Potter theme park.
Throughout the 1950s to the 1970s, we had the auto boom in the US paired with the development of air travel. During the auto boom, cars became bigger and more comfortable, as well as more affordable, and gas prices were inexpensive as well. Our government also invested a great deal of money in the development of our highway systems, some of which replaced train lines. Air travel was really what finally brought the commerce of tourism to the US, making in easier for people from around the world, not just Canada and Mexico to travel to the States.