Tourism in the United States and its possessions is also big business. It is the most important industry in Hawaii, for instance, and accounts for 75 percent of the economy of the American Virgin Islands. In fact, according to the American Society of Travel Agents, tourism now constitutes the first, second, or third most important industry in 46 of the 50 states. No doubt, like the stately passenger liners that were converted into hotels or year-round cruise ships once the days of their transatlantic runs had ended, Americans will adjust their travel plans to whatever circumstances exist. Tourism differs from travel as leisure differs from labor.
People travel for any number of reasons, from business to war or religion.
Tourism, however, is travel undertaken for pleasure. Depending on individual tastes, it may involve rest and relaxation, sports, cultural exchanges, educational and aesthetic experiences, or eating and shopping. As a modern multimillion-dollar business, it caters to the tourist's need for transportation, accommodation, food, entertainment, recreation, health, souvenirs, and social contact. Mass tourism is a relatively modern phenomenon, but travelers have reacted as tourists, regardless of the purpose of their journeys, since the beginning of recorded history. To write his history of the war between the Greeks and the Persians, Herodotus personally visited many of the areas making up the Persian Empire.