Tennessee's Interstate System - Frequently Asked Questions

When did the idea for an interstate begin? 
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.
How was this federal concept accepted in the states?
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.
Funding issues slow the plan
The Federal-Aid Highway Act of 1952 authorized funds on a 50/50 state/federal matching level. These were the first funds dedicated to this cause. But even then, the amount ($25 million) was not enough. When President Eisenhower assumed office in 1953, only 6,000 miles had been completed at a cost of $955 million.
Eisenhower’s true role
Recalling how quickly German (and later, Allied) troops could move around that country in World War II on the autobahns (built in 1935), Eisenhower pushed for a national highway system. While he wanted such a system, he didn’t start it as is commonly believed. What made the idea catch on, and why he often receives a lot of credit for the interstate system, was his ability to convince people that this was a national, not state, issue.
Increased funding speeds up plan, standards are established
The Federal-Aid Highway Act of 1956, created today’s Interstate system and was signed by President Eisenhower on June 29, 1956 in a hospital room without any fanfare. The federal government would pay 90% of the cost, because it was realized now that this project was national in scope. It further called for road design standards to accommodate traffic levels forecast for 1975, which was later modified to a 20-year forecast. In 1966, all Interstates were required to be at least four lanes with no at-grade railroad crossings. Existing toll roads could continue as Interstate toll roads provided they met Interstate standards. In 1991, the U.S. Congress finally decided to repay states with toll roads that later became Interstates.
Initially, the system was to cover 41,000 miles of road, including 2,000 miles of existing toll roads. It was to be completed in 1975. As time passed it became obvious that goal would not be reached. In 1975, the system had about 35,000 miles of roadway.
Who is responsible for the Interstate System?
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.
What was the first Interstate in the nation?
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.
What is the official name of the interstate system?
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.” 
On what famous list does the Interstate system appear?
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. 
What is the longest Interstate?
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. 
What is the shortest Interstate?
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. 
What is the highest Interstate route number?
The highest interstate route number is I-990 north of Buffalo, NY. 
What is the lowest Interstate route number?
The lowest interstate route number is I-4 across Florida. 
Is there any state that does not contain Interstates?
Yes. The only state without any interstate routes is Alaska. 
How many people travel on the Interstate system daily? 
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. 
How many bridges exist on the Interstate system?
More than 55,000 bridges have been built on the interstate system.
How are interstates numbered?
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.
There are a total of 58 one-digit or two-digit interstates in the continental U.S. Of those 58, 27 run primarily east-west. The other 31 go primarily north-south. There are three interstates in Hawaii (H-1, H-2, and H-3) and no interstates in Alaska.
If the first number of a three-digit interstate route number is odd, it is a spur into a city. If it is even, it goes through or around a city.


Sources: A 1996 special issue of Public Roads, a publication of the Federal Highway Administration, and The Best Investment a Nation Ever Made by the American Highway Users Alliance. Public Roads Archives, Milestones for US Highway Transportation and the Federal Highway Administration.