The Interstate Highway System (hereafter called IHS) was not only a huge structural undertaking that altered the landscape of America. It brought about a social and economic upheaval that we still do not fully appreciate.
Originally, the Federal-Aid Highway Act of 1938 called for a study of a six route toll network. FDR felt there should be three east-west routes and three north-south routes.
But as Congress and succeeding Presidents studied the matter, the concept grew in scope and size. In 1956, President Eisenhower signed legislation establishing the National System of Interstate and Defense Highways. By now, the IHS was seen to require 41,000 miles of roads.
Note the words Defense Highways. The Department of Defense played a major role in the development and construction of the IHS. Its purpose was to allow for mass evacuation of cities in the event of a nuclear attack. The DOD went even further by requiring that one mile in every five miles had to be straight to be available as airstrips in the event or war or other emergencies.
The IHS committed this country to the automobile as the primary source of transportation. As a result a nationwide system of rail and bus transportation began to decline and disappear.
The automobile industry became, as the economists like to say, the "backbone of our economy". Instead of building or keeping the diversified manufacturing we had, we set the stage for an economy dependent on one industry for fiscal health, and it created a demand for and dependency upon oil that had long term consequences that are still being felt today.
Social upheaval followed as well. Freeways cut through cities, nearly always through the poorer neighborhoods. These dislocations not only left people homeless but without a grounded sense of place as well.
The complex and organic network of railroads and traditional highways that had developed over time linking communities to retail centers, workplaces, schools, etc. were bypassed. In time, it was seen that a new arrangement of how a community lives had to be found and put in place.
This explains the growth of suburbs and box stores and shopping malls. This also demonstrates how the new arrangements created a demand for even more cars. The one-car family with a one-job provider is an anachronism today. Every one needs to have a job and everyone needs their own car to get there.
And so we have these 14 lane super-highways in metropolitan areas filled with cars moving slower than horses that have been nicely described by James Howard Kunstler as "automobile slums".
Fifty years ago it was very different!