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US Interstate Highway System
Also, known as the Dwight D Eisenhower National System of Interstate and also the Defense Highways system. This is a system of controlled accesses highways and are in all fifty United States and Puerto Rico. When Dwight D Eisenhower became president in 1953, his administration started developing an Interstate Highway System. From this development the Federal Aid Highway Act of 1956 was passed.
Map of proposed Interstate System in 1955
The Federal Aid Highway Act was to create an all-freeway system of roads. All roads were built with the same standards. Most of the funding for these freeways were funded by the federal government. But the ownership is retained by the state they were built in.
In 1992 construction of the original Interstate system was said to have been completed. With a cost of $114 billion in 1956 money. That amount in 2023 money would be over $1.2 trillion. Since 1992 additional funding has been passed to expand the system and this expansion will continue into the future.
Major milestones in the construction of the Interstate Highway System:
· In 1974 Nebraska becomes for the first state to complete a section of interstate which was I 80.
· In 1979 the last section of I 5 was completed. This connected Mexico to Canada through Washington, Oregon, and California.
· In 1986 I 80 was completed from the Atlantic to the Pacific oceans.
· In 1990 I 10 was completed from the Atlantic to the Pacific oceans.
· In 1991 I 90 became the last Atlantic to Pacific to be completed.
· In 1992 the last section of I 70 was completed.
The numbering of the interstates was developed by the American Association of State Highway and Transportation Officials (AASHTO). One-digit and two-digit interstates are considered mainline. Where the odd numbered run from north to south and the even numbered run east to west. They also have three-digit interstates. If it starts with an odd number, it is considered a short spur. Even numbers are loops around major metro areas.
An interesting statistic found is in 2020 approximately one-quarter of the vehicle miles driven were on the Interstate Highway system.
Just for comparing to the map above which was 1955. Here is a 1938 map.
We wrote a blog on the US Route Numbers here is the link to it:
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