New Orleans is a major center of domestic and international freight traffic. In volume of domestic and foreign cargo handled, however, the Port of South Louisiana, which stretches 54 miles along the Mississippi River, is the largest tonnage port in the Western Hemisphere and 3rd in the world. Although Louisiana's roads remained poor until the 1930s, the state was one of the nation's major rail centers by the end of the 19th century, and New Orleans was one of the first cities to develop a mass transit system.
Several short-run railroads were built in Louisiana during the 1830s. The first of these, and the first rail line west of the Alleghenies, was the Pontchartrain Railroad, which opened, using horse-drawn vehicles, on 23 April 1831. New Orleans was connected with New York before the Civil War, with Chicago by 1873, and with California in 1883 via a line that subsequently became part of the Southern Pacific. Railroads soon rivaled the Mississippi River in the movement of goods to and from New Orleans. There were six Class I line-haul railroads in Louisiana in 2000, and total railroad mileage was 3,192 route mi (5,137 km), of which about 90% was Class I track. That same year, originated tonnage of petroleum products transported by rail totaled more than 57 million tons, and chemicals totaled more than 16 million tons. Amtrak provides passenger links with Los Angeles, Chicago, and New York and carries passengers from nine stations through the state. The New Orleans and Carrollton Railroads, a horse-drawn trolley system, began service in 1835; 59 years later, electric trolleys came into use.
Louisiana's first road-building boom began after Huey Long entered the statehouse. When Long took office in 1928, the state had no more than 300 mi (480 km) of paved roads; by 1931 there were 1,583 mi (2,548 km). At the end of 2000, Louisiana had a total of 60,900 mi (98,009 km) of public roads, over 75% of them rural. Also in 2000, 1,964,694 automobiles and 1,570,804 trucks were registered in the state, and 2,759,120 drivers' licenses were in force.
Early in the nation's history, the Mississippi River emerged as the principal route for north–south traffic, and New Orleans soon became the South's main port. The advent of the steamboat in 1812 solved the problem of upstream navigation, which previously had required three or four months for a distance that could be covered downstream in 15 days. (Barges moved by towboats eventually supplanted steamboats as cargo carriers.) An important breakthrough in international transportation was the deepening of the channel at the mouth of the Mississippi by means of jetties, the first of which were completed in 1879. The port of New Orleans is served by more than 100 steamship lines, 20 common carrier lines, and about 100 contract carrier barge lines. The Louisiana Offshore Oil Port (LOOP), the first deepwater oil port in the US, was opened in 1981. Located south of New Orleans in the Gulf of Mexico, the supertanker facility has a designed capacity of 1,400,000 barrels of oil a day. Large ports include Baton Rouge, with a tonnage of over 65.6 million tons in 2000; New Orleans, with 90.8 million tons; and the Port of Plaquemines, with 59.9 million tons. The Port of South Louisiana, handling 217.8 million tons in 2000, is the US's busiest port.
In 2002, Louisiana had 232 private and public airfields. The busiest was the Louis Armstrong New Orleans International Airport. Louisiana also had 229 heliports and 17 seaplane bases.