How it all Started:
In the summer of 1919, an Army Convoy called the First Transcontinental Motor Convoy left Washington DC for a 3,200 mile road trip to San Francisco. This trip included approximately 80 vehicles. The purpose of this trip was to road test the vehicles and see how difficult it would be to move a military convoy across the US on existing roads. The trip took 62 days, averaging a little over 52 miles per day.
A Lt. Col. Named Dwight Eisenhower was assigned to this convoy as an observer. His report to the Army leaders noted the poor condition of roads and bridges in many areas, mostly the Midwest and Western sections of road. He noted that some sections of the Lincoln Highway in Utah and Nevada were in such poor condition that an investigation should be done before additional government funds should be spent.
The Early Years:
By 1933, Franklin D. Roosevelt was president and he understood the importance of good roads and suggested three east-west and six north-south routes. The concept of the Interstate Highway System started from two reports to the US Congress. In 1938, The Bureau of Public Roads (BPR) approved a report suggesting no more than three east-west and three north-south “super highways”. The Toll Roads and Free Roads report of 1939 would be based in the 1938 information.
In 1944, The Interregional Highways Report was published. These reports recommended construction of what the 1939 report called a “system of direct interregional highways, with all necessary connections through and around cities, designed to meet the requirements of the national defense in time of war and the needs of a growing peacetime traffic of long range”. The Public Roads Administration (PRA) in 1946 was responsible for formulating an interstate highway system based on recommendation from the states. A year later, a 37,681 mile system including urban thoroughfares and urban bypasses was approved.
President Roosevelt started the New Deal, a series of programs designed to help put people back to work following the Great Depression. Some of these programs did supply money for highway work, but that was mostly for repair and smaller improvements, not new roads.
In 1944, The Federal-Aid Highway Act was approved. This Act provided $225 million a year for new highways and another $150 million a year for secondary/feeder roads. This money was never actually put into road construction, it was placed into accounts of the US Treasury for Interstate Highways. The money was not spent until passage of The Federal-Aid Highway Act of 1956.
Major Funding Work Begins:
In 1953, Dwight Eisenhower, the Lt. Col. Observer on the 1919 First Transcontinental Motor Convoy was President of the United States of America and by this time his vision was a network of new highways crossing America north to south and east to west. He would later persuade Congress to enact the 1956 Federal-Aid Highway Act creating what we now call the Interstate Highway System. The First Transcontinental Motor Convoy and his years in Germany and seeing the Autobahns during World War II gave him the opportunity to see what needed to be done in the US.
Prior to Eisenhower becoming President, The Public Roads Administration (PRA) along with the American Association of State Highway Officials approved design standards for what would become the Interstate Highway System. These standards were approved in 1945 and did not call for a uniform design for the entire system, but for uniformity for conditions such as traffic, population, topography and other factors. It did not call for four lanes with limited access at all locations.
In July of 1954, Eisenhower’s plan was presented. The plan would involve each level of Government (Federal, State, County and City) to contribute to upgrading the Nation’s entire road network over a 10 year period. In 1955, the estimated cost of the new Interstate highway was $25 billion and in 1956, The Federal-Aid Highway Act was passed by Congress. This Act increased the total miles to 41,000 and authorized $25 billion per year for fiscal years 1957 through 1969. This Act included the money that was not spent from the 1944 The Federal-Aid Highway Act. Also in 1956, The Bureau of Public Roads (BPR) and The American Association of State Highway Officials (AASHO) agreed to some additional design standards for the Interstate Highway System. All cross traffic would go over or under the route and consist of divided highways with four or more 12 foot wide lanes. In sparsely settled rural areas where traffic volume would be low, the standard would be relaxed, with at-grade crossings permitted in some cases. Two lane sections with one lane in each direction would be built on one side of the right-of-way so additional lanes could be added when traffic was warranted.
Highways would be designed for speeds of 50 MPH in mountain terrain, 60 MPH in rolling terrain and 70 MPH in flat terrain. Bridges and overpasses would be built with at least 14 feet vertical clearance.
Interstate Highway Construction Begins:
The first two projects started in 1956 on I-70 with 3.1 miles in St. Charles County, MO and 8 miles just outside of Topeka KS.
Also in 1956, construction started on a 7 mile long test section. The pavement and bridge designs largely follow the results of testing by the American Association of State Highway Officials (AASHO). The test section included 7 miles of two lane pavements and 6 loops. Half was concrete and half was asphalt. The over 800 test sections used a range of sub-base, base and surface thickness and included several short bridge spans. Test traffic started in October of 1958 using both light weight and heavy weight vehicles. Testing ended in November 1960. The AASHO testing is a landmark in highway and bridge design. The straight sections of the test sections were not wasted, as they became part of I-80 in Illinois
By January of 1961 when Eisenhower left office, 10,440 miles on Interstate Highway were open to traffic at a cost of over $10 billion. 75% of the originally planned highway still remained to be built.
On October 14, 1992 the Interstate Highway System was declared finished with the completion of I-70 in Colorado, however it was not really finished. There were still two gaps, one on I-95 in New Jersey that was not completed until 2018 and another on I-70 in Pennsylvania that has still not been completed.
Today the Interstate Highway System is 46,876 miles long and includes all 50 states. It will never be completely finished as new connector routes will be needed as the population increases over the years.