Railroads have lost not only the largest share of intercity freight traffic, their chief source of revenue, but passenger traffic as well. Despite an attempt to revive passenger transport through the development of a national network (Amtrak) in the 1970s, the rail sector has continued to experience heavy losses and declining revenues. In 1998 there were 9 Class I rail companies in the United States, down from 13 in 1994, with a total of 178,222 employees and operating revenues of $32.2 billion. In 2002 there were 212,433 km (132,005 mi) of mainline routes, all standard gauge. In 2000, Amtrak carried 84.1 million passengers.
The most conspicuous form of transportation is the automobile, and the extent and quality of the United States road-transport system are without parallel in the world. Over 213 million vehicles—a record number—were registered in 2000, including more than 127.7 million passenger cars. In 2000, there were some 4,346,068 motorcycles registered as well.
The United States has a vast network of public roads, whose total length as of 1998 was 6.37 million km (3.9 million mi). Of that total, about 5,733,028 km (3,562,503 mi) were paved, including 74,091 km (46,040 mi) of expressways. In 1999, federal and state funds for highway construction were $95.5 billion. In 2000, federal funds for highway construction were $27.7.8 billion. The United States also has 41,009 km (25,483 mi) of navigable inland channels, exclusive of the Great Lakes.
Major ocean ports or port areas are New York, the Delaware River areas (Philadelphia), the Chesapeake Bay area (Baltimore, Norfolk, Newport News), New Orleans, Houston, and the San Francisco Bay area. The inland port of Duluth on Lake Superior handles more freight than all but the top-ranking ocean ports. The importance of this port, along with those of Chicago and Detroit, was enhanced with the opening in 1959 of the St. Lawrence Seaway. Waterborne freight consists primarily of bulk commodities such as petroleum and its products, coal and coke, iron ore and steel, sand, gravel and stone, grains, and lumber. The US merchant marine industry has been decreasing gradually since the 1950s. In 2002, the United States had a merchant shipping fleet of 258 vessels of more than 1,000 gross registered tons with a combined GRT of 8,259,914.
In 2001, the United States had an estimated 14,695 airports, of which 5,1631 had paved runways. Principal airports include Hartsfield at Atlanta; Logan International at Boston; O'Hare International at Chicago; Dallas-Fort Worth at Dallas; Detroit Metropolitan; Honolulu International; Houston Intercontinental; Los Angeles International; John F. Kennedy, La Guardia, and Newark International at or near New York; Philadelphia International; Orlando International; Miami International; San Francisco International; L. Munoz Marin at San Juan, Seattle-Tacoma at Seattle, and Dulles International at Washington. Revenue passengers carried by the airlines in 1940 totaled 2.7 million; by 2001, the figure exceeded 619 million for US domestic and international carriers, along with 28,042 million freight tonkm (17,425 million freight ton-mi).