Tennessee's Interstate System - Frequently Asked Questions

The idea for an interstate highway system was first conceived in the 1930s. President Roosevelt backed the idea as a way of providing jobs. The Federal-Aid Highway Act of 1938 directed the chief of the Bureau of Public Roads (precursor to today’s Federal Highway Administration) to study the feasibility of a six-route national toll road network. The study did not recommend a national toll road system since the then-existing traffic levels would not support its cost. It further recommended a 26,000-mile non-toll “inter-regional” highway network. In high-traffic areas, it would have two lanes in the same direction and limited-access design. The recommendation essentially asked for a 1930s version of today’s Interstate system.

It was not immediately embraced. The Federal-Aid Highway Act of 1944 created a 40,000-mile “National System of Interstate Highways,” but without national importance and no increase in federal funding. Construction of the system began in August 1947, but without increased federal support, many states balked at the idea. In addition, road design standards were not always uniformly applied as construction began.

President Eisenhower, Senator Albert Gore Sr., Representatives George H. “Highways” Fallon and Thomas Boggs, along with Frank Turner, then chief of what is now called the Federal Highway Administration, are commonly seen as the fathers of the Interstate system. Tennessee senator and Carthage native, Gore had a major role in the political battle for the Interstate Highway System. Along with Fallon from Maryland, Gore was a key congressional player in reaching the compromise that led to the 1956 Federal-Aid Act, often called the Fallon-Gore Act. The act provided $25 billion for twelve years to fund the National System of Interstate and Defense Highways. In honor of his role in the Interstate system, part of I-65 in Tennessee has been named the Albert Gore, Sr. Memorial Highway.

There is some disagreement over when the first Interstate was created. Pennsylvania, with its Turnpike, Missouri, with its Interstates 44 and 70, and Kansas with its Interstate 70, all lay claim to being the first. The first three contracts under the new program were signed in Missouri on August 2, 1956. However, all of these roads were either started before the Interstate Act was approved, or were upgrades of existing roads. The Pennsylvania Turnpike opened on October 1, 1940, and was the first limited-access, divided highway in the country.

The original name was the “National System of Interstate and Defense Highways.” In October 1990, President George H. W. Bush signed legislation changing its name to the “Dwight D. Eisenhower System of Interstate and Defense Highways.” 

In February 1994, the American Society of Civil Engineers declared the Interstate system one of the “Seven Wonders of the United States.” Other wonders include the Hoover Dam and the Golden Gate Bridge. The economic impact of the Interstate system, the world's largest public works project, is incalculable. There is hardly one aspect of American society that hasn’t been affected by the Interstates. 

The longest interstate is I-90, which runs from Boston to Seattle, a total of 3,081 miles. At 75 mph it would take you 41 hours of nonstop travel to cover that distance. The second longest stretch of interstate is I-80, which covers the 2,907 miles between New York City and San Francisco. Interstates 5, 10, 15, 20, 25, 35, 40, 70, 75, 80, 90, 94 and 95 are all more than 1,000 miles long. 

The shortest interstate is I-878 in New York City, which is all of seven-tenths of a mile long. That’s just 3,696 feet. 

The highest interstate route number is I-990 north of Buffalo, NY. 

The lowest interstate route number is I-4 across Florida. 

Yes. The only state without any interstate routes is Alaska. 

Interstates carry nearly 60,000 people per route-mile per day, 26 times the amount of all other roads, and 22 times the amount of rail passenger services. Over the past 40 years, that's the equivalent of a trip to the moon for every person in California, New York, Texas, and New Jersey combined. 

More than 55,000 bridges have been built on the interstate system.

East-west interstate route numbers end in an even number. North-south routes end in an odd number. The basis for this numbering system goes back to the 1920s.