Over the Road August 2023

A Lesson about our Interstate System

Ellen Voie

Warmer temperatures bring orange cones and construction signs to our nation’s highways. Although these barriers might be frustrating, they are needed to maintain nearly 50,000 miles of interstate highways.

How familiar are you with how our roads were designed and how to understand our nation’s interstate numbering system? If you’ve always relied on your GPS instead of a folded map, then you may not know the reasoning behind our highway system.

In 1908 Henry Ford introduced the Model T to America. Until that time, the roads were better suited for horses and buggies than tires. The need for paved roads led to the creation of the Federal Aid Road Act of 1916, but progress was delayed during World War I. In 1921 the Federal Highway Act provided funding for two highways to be built by state highway agencies.

It wasn’t until 1956 when the Federal Aid Highway Act authorized a network of 41,000 miles of interstate highways to be funded through a three-cent per gallon tax on gasoline. This was the goal of President Eisenhower, who had been impressed by the German high-speed roads he used in World War II.

Eisenhower wanted a coast-to-coast highspeed interstate system with overpasses and bridges to avoid intersections and stop signs that would slow a motorist’s travels. The medians were designed to separate traffic and the signs were standardized.

These roads are maintained by the individual states, which also set the speed limits within their borders. This changed for a few years from 1975 to 1986, in an effort to conserve fuel by slowing down the traffic.

The Interstate System has an easy-tounderstand numbering method, but many people today are unaware of what these numbers mean. All the primary interstates are two-digit numbers less than one hundred. The north and south highways have odd numbers while the east and west highways have even numbers. The numbers start in the west and become larger, and the north and south roads increase as you travel north.

There is a total of 77 interstate highways in the United States. The longest is I-90 which begins in Seattle, Washington and ends in Boston, Massachusetts traversing thirteen states for a total of 3,020 miles.

Interstate numbers that are divisible by five are coast-to-coast or border-to-border roads, such as I-90.

The shortest interstate highway is H2 which is located in Hawaii with only eight miles from one end to the other. The shortest highway located in the United States is I-87, which runs thirteen miles from Raleigh to Wendell in North Carolina.

To travel around cities, you will find three-digit roads which include the last two digits of the connecting highway. For example, in Washington DC I-95 will connect you to I-395. For loops and bypasses that start and end with the same numbered highway, the first number will be an even one as opposed to those that might connect to only one other interstate highway given an odd first number. More confusing are the bypass highways on one interstate which results in multiple three-digit highways around cities, including I-395 which can be found in seven locations.

Although the Interstate System was created to connect the United States, there are three land masses that are not part of our 48 contiguous states. Alaska, Hawaii, and Puerto Rico have their own interstate systems, but the highway numbers begin with the letters A, H or PR.

There are still new lanes being built, but these are much shorter than the original roads. The most recent are highways which were built in 2017 and include I-14 in Texas, I-11 in Colorado, and I-87 in North Carolina.

Professional drivers are much more knowledgeable about the markings on the interstate system and know to reference mile markers to report their location. Most states number their exits to correspond to the nearest mile marker, but some states have sequential exit numbers which are typically found in the northeast. Multiple exit numbers that are close to a mile marker include letters such as a, b, or c to remove confusion over which off-road travellers should take.

President Eisenhower had a vision to connect our vast country by creating an easy-to-understand and easy-to-use interstate system. The orange cones and construction areas will be around as long we continue to wear these roads down with both our cars and our trucks on the highway.

Ellen Voie
President/CEO/Founder of
Women In Trucking, Inc.
ellen@womenintrucking.org www.womenintrucking.org

Mission: Women In Trucking was established to encourage the employment of women in the trucking industry, promote their accomplishments and minimize obstacles faced by women working in the trucking industry.