On July 7, 1919, a group of 24 officers and 258 enlisted men of the U.S. Army Motor Transport Corps departed Washington, D.C. bound for Oakland, California. This convoy of 81 vehicles would cover the 3,250 miles in 573.5 hours, averaging just 5.6 miles per hour, arriving in Oakland a week behind schedule on September 5. The amount of time the trip took was not surprising – along the way the convoy would repair 88 wooden bridges, take 6 rest days, and travel on dirt roads between Illinois and Nevada.
The mission was largely an exhibition for the Army. The Motor Transport Corps used the trip for recruitment and to show the public what the motor vehicle, then still a relative novelty, could do for military purposes. But it also had more practical aims. Military and civilian observers were able to discern the relative strengths and weaknesses for a variety of vehicles over a variety of terrains. But perhaps the most important objective was to demonstrate a dire need for a national highway system.
One of the observers, then Brevet Lieutenant Colonel and future president Dwight D. Eisenhower, would remember the Motor Transport Corps convoy some 37 years later. America’s roads were a “succession of dust, ruts, pits and holes,” according to Eisenhower. That experience and his experience with the German Autobahn during World War II gave Eisenhower a unique perspective into what a national highway system could do for the country.
What would eventually become the interstate highway system resulted from a trio of Federal Aid Highway Acts, passed in 1921, 1944 and 1956. The first set of highways created were the United States Numbered Highway System. Although the numbering system was “nationalized” and most of the routes crossed state borders, the highways have always been built and maintained at the state and local level. The legislation that created these highways focused more of financing rather than true standards. Despite this, the “US” routes proved popular with the growing country, allowing for economic growth, especially in the West.
When Eisenhower assumed the presidency in 1953, the US was already locked in a Cold War with the Soviet Union. Eisenhower saw an enhanced highway system as essential for national security. Now there is some debate about the national security role of a highway system. While it is likely that Eisenhower thought that highways could be used for landing airplanes during a national emergency, the idea that one in five miles of the interstate system had to be straight for this purpose is just a myth.
The Federal Aid Highway Act of 1956 was signed by Eisenhower establishing the interstate highway system. But it did more than just establish the system, it standardized our highways for the first time at the federal level. These standards included controlled access to and from the highway, barriers or medians between opposing directions, sign specifications, shoulder and lane widths, among others.
The legislation also established the numbering system and route convention that is still in effect today:
- In general, the numbering of routes increases from west to east, and from south to north. For example, Interstate 5 is the westernmost south-north route in the system. Interstate 8 is the southernmost west-east route in the system (that actually runs across state lines).
- Interstate routes are identified by standard signage nationwide, to distinguish them from state or US routes. The letter I and the number are often used when referring to these routes.
- Actual interstate routes are generally one or two digit numbers, with three digit routes being spur routes off of their parent routes. The last two digits of a spur route refer to the parent route – for example I-405 that bypasses Seattle and the I-705 spur in Tacoma, the “05” refer to the parent route of I-5.
- Odd route numbers are reserved for south-north direction routes, while even numbered routes are reserved for west-east direction routes.
- Mile markers on interstate routes (and most highways in the United States) follow route convention. Mile markers increase when going west to east, and when going south to north. Thus if you enter Arizona headed west on I-10 at the New Mexico border and you see milepost 390, you know it is 390 miles to the Arizona border with California.
- Exit numbers correspond to the mile in which they are located.
With an estimate cost of $114 billion, the interstate system was declared complete in 1992 with the completion of the final leg of I-90 into Seattle. But it has been 70 years since the system’s establishment, and some of the highways are nearly that old. The system Eisenhower helped establish is getting old and we need a renewed emphasis to keep that system in good repair. And that’s not just bridges – it is pavement, it is congestion relief, it is fixing substandard vertical clearance issues. Are you up for the challenge?
Happy New Year from TheBridgeGuy!
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