Building the United States Interstate System

How and Why It Happened

Dec 06, 2022

The Interstate Numbering System

Issue #190 American History December 6, 2022

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If you travel any distance by car, you have used the Interstate Highway System. The “Interstate,” as it is commonly known, is a network of controlled-access highways and is a part of the National Highway System.

The Interstate extends throughout the 48 continuous states, and also continues those routes into Hawai’i, Alaska, and Puerto Rico.

In 1956, President Dwight D. Eisenhower signed the Federal Highway Act, based on his belief that the U.S. needed better highways for automobile safety, better defense, and economic growth. Eisenhower initially proposed that the Interstate be funded completely by tolls, but was convinced that would not be feasible outside of heavily populated areas.

Eisenhower then proposed using public bonds as financing, but the Democrats in Congress objected. Finally, the initial building of the Interstate was funded by the Highway Trust Fund, which was funded by a gasoline tax.

The Federal Aid Highway Act of 1956 stipulated that the federal government would pay for 90% of the cost of the construction of interstate highways. Each highway was required to be at least four lanes wide and have no at-grade crossings.

The history of National Highways

In the early 1900s, after Henry Ford implemented the efficient assembly line method for building cars, automobiles became much more affordable for the majority of Americans. The roads over which those cars were driven were mostly very rudimentary and even often shared with horse-drawn carriages and wagons.

The United States federal government first started funding roadways through the Federal Aid Road Act of 1916 and the Federal Aid Road Act of 1921.
In 1926, The United States Numbered Highway was established, however most roads were still state-funded and maintained and there were few national standards for the design of roadways.
East-West Highways have even numbers, and North-South Highways have odd numbers.
The numbering system of Interstate Highways designates that primary Interstates are assigned one- or two-digit numbers and shorter routes that branch off of longer ones are assigned three-digit numbers where the last two digits match the parent route.
Many densely populated urban areas that primarily contained Black and other minorities and older well-established neighborhoods and business centers were completely destroyed by the construction of the Interstate Highway System, often on purpose.
The Interstate System accelerated the “white flight” from the cities to the suburbs in the post-WWII era through the 1970s. Many of those new suburbs had restrictive covenants to deliberately keep out non-white residents.
Although the federal government paid for most of the construction costs of the Interstate Highway System, the highways themselves are owned by the states in which they were built. Toll roads were initially banned on the Interstate, but some toll roads were grandfathered into the system or added because of subsequent legislation in some states.
The final construction of the Interstate Highway System was completed in 1992 at a cost of $535 billion in 2020 dollars.
In the mid-1950s, more people began to use airplanes instead of trains for long-distance national travel and freight deliveries.
The Interstate System helped to grow the trucking industry and the tourism industry, but rural areas were mostly shut out of access to the Interstates because shoppers used the new roadways more often and new factories were built near the Interstates.
The Interstate Highway System was a great help to the southern states where major highways were inadequate. The new roadways helped to facilitate the relocation of heavy manufacturing and auto plants and also the development of Southern-based large corporations such as Walmart (Arkansas) and FedEx (Tennessee).
The Interstate Highway System also led to the rapid decline of public transportation systems in many areas of the country and, of course, more gas-powered cars led to more fossil fuel pollution. Today, more climate-friendly electric cars are being built and many cities are expanding public transportation routes instead of building more roads that connect to the interstate.

For over twenty years, Keith and I have driven from Detroit to just outside of Baltimore for our annual Thanksgiving Week Family Reunion. Michigan does not have toll roads, but Ohio, Pennsylvania, and Maryland do have toll roads.

A major change that we have noticed in the past few years is that toll booths with human employees have been eliminated in Maryland and Pennsylvania. Instead, people who travel the Interstate frequently can buy a pre-paid EZ Pass that is scanned by a camera when placed on the dashboard.

Infrequent travelers like us are now sent an invoice. Our car’s license plate is photographed as we pass through where the toll booths used to be. Then, a few weeks later, we get a bill in the mail using the address of our vehicle registration. If the invoice is not paid by the due date on the invoice, drivers risk a citation and civil penalty that can lead to a suspension of the vehicle registration.

The construction of the Federal Interstate Highway System changed the American culture, patterns, routines, and economics more than almost any other federal program.

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