The United States, the fourth largest country by land area, has developed an extensive transportation system to serve its 300 million residents and 7 million business establishments. Americans travel a great deal as they go to and from work, run errands and shop, transport children, visit their family and friends, take vacations, enjoy leisure time pursuits, and engage in other pursuits. Whether they travel long distance or locally, they overwhelmingly use personal vehicles (cars, minivans, sport utility vehicles, etc). Nearly 90 percent of their long distance trips are in personal vehicles, followed by airplanes at 7 percent, and intercity bus at 2 percent. They use personal vehicles to make 87 percent of their daily trips, followed by walking (9 percent of daily trips), transit, and other modes. U.S. businesses depend on the transportation system as they move their goods to markets here and abroad, set up supply chains and distribution networks, and send employees throughout the country and world to conduct business. Trucks are the most widely used means of transporting freight in domestic transportation, but rail, water and pipeline together account for a majority of ton-miles, and, while the tonnage is small, air freight is rapidly growing, especially for high value commodities that need to be delivered quickly. Both passenger travel and freight shipments require an interconnected system of transportation modes to function effectively.