At the beginning of the 20th century, an uninterrupted system of nationwide highways did not exist. Beginning in 1811, a National Road had been constructed between Cumberland in western Maryland and Vandalia, the then capital of Illinois, to facilitate immigration to the frontier; however, this road fell into disrepair. It wasn't until the late 1930s that interest in a transcontinental system of highways began to grow. President Franklin Roosevelt urged the construction of a network of highways as a way to provide jobs for people out of work.

Congress Acts

The Federal-Aid Highway Act of 1938 was the first serious attempt to develop a national roadway system. The legislation directed the Bureau of Public Roads to study the feasibility of a toll-financed system of three east-west and three north-south superhighways. From this study officials determined that the amount of transcontinental traffic was insufficient to support a network of toll highways. Instead they recommended a 43,000-kilometer (26,700-mile) network of nontoll highways.

Congress passed further legislation in the form of the Federal-Aid Highway Act of 1944. This act expanded the network to 65,000 km (40,391 mi) and charged state highway agencies and the Department of Defense with planning nationwide routes that would directly connect the country's major cities and industrial centers. However, no specific funds were authorized for construction, and progress was slow.

Eisenhower Makes It a Reality

Dwight Eisenhower had long realized the importance of highways, even before he became president in 1953. In 1919 as a young lieutenant colonel in the army he had accompanied the first transcontinental military motor convoy from Washington, DC, to San Francisco. Like most American motorists, the soldiers traveled on dirt roads and crumbling bridges; it took about two months for them to cross the country. And years later, during World War II, he observed the advantages of the German autobahn network, which made for safe and efficient mobility.

The Federal-Aid Highway Act of 1954 set aside $175 million for the construction of an interstate highway system. However, even more money was needed for the system that Eisenhower envisioned, and he continued to press for funds. Two years later, the expanded Federal-Aid Highway Act of 1956 authorized a budget of $25 billion, of which the federal share was to be 90%.

A Standard Design

The legislation of 1956 also provided for an extended network of 66,000 km (41,012 mi) and nationwide design standards, including:

• a minimum of two lanes in each direction
• lanes that were 12 ft in width
• a 10-foot right paved shoulder
• design speeds of 50–70 mph

Further legislation over the years continued to expand the total length of the system, which now stretches for more than 74,600 km (46,380 mi). In 1990, in recognition of President Eisenhower's pivotal role in building the national system of interstate highways, President George Bush signed legislation officially renaming it the Dwight D. Eisenhower System of Interstate and Defense Highways.

Naming the Interstates

The procedure for naming the highways is systematic. Major routes are designated by single- or two-digit numbers. If a route runs north-south, it is given an odd number, and if a route runs east-west, an even number. For north-south routes, numbering conventions begin in the west. Thus I-5 runs north and south along the West Coast, while I-95 runs north and south along the East Coast. For east-west routes, numbers begin in the south.

Major routes usually traverse cities and are the shortest and most direct line of travel. Connecting interstate routes that travel around a city carry three-digit numbers.