Fifty Years on the Interstate

Nicholas Malinak

                        Human development carries with it the inevitable reality of an impact on the environment; questions of the size, manner, and importance of those developments define the scope of current environmental debates.  Rarely, but significantly, development carries with it the promise of predominantly positive impacts to the environment and human society.  If the progress of human civilization must coexist with the needs of a fragile environment, then the process of development must welcome compromises that protect the environment, just as environmental protection must embrace the certainty of continued development.

            One who is environmentally minded can not help but notice that the world around them contains buildings, mines, dams, roads, and many more signs of human civilization that impact negatively on the native environments on which they encroach.  It is easy to see a road that carves through a wood and denounce it as a scourge to the natural world, but it is far more difficult, and more rewarding, to see the greater evil which has been avoided.  If we use this lens of principle and pragmatism to view the impact of human development on the environment, we can evaluate our environmental future with clarity of vision.

            The development of roads has had a profound and primarily negative impact on the environment of the United States [1].  Not only do roads themselves bring environmental destruction to their banks, but they encourage other forms of environmentally harmful development.  Roads, however, are an inescapable reality of modern society, and as long as there are cares in which to drive, their will be roads on which to drive.  The impact of those roads, however, can vary greatly.  The Eisenhower Interstate System is the lifeblood of the national network of almost 3.98 million miles of roads [2] and has had a major impact on the environment of all fifty states.  When compared to the alternative of an ad-hoc road network, the Interstate System has environmental impacts that shift its net impact.

s           The large-scale designation of a national network of roads was first set in motion with the Federal-Aid Highway Act of 1944 which designated 40,000 miles for the system [3].  However, it would be take more than a decade and the strong backing of President Eisenhower until the idea became a reality with the passage of the Federal-Aid Highway Act of 1956.  While limited-access highways had begun to appear prior to the Interstate System, and the nation already had a system of numbered highways, the new network would provide a unified and standardized backbone to the nation’s growing body of motorized transportation.  On September 15, 1991, after 35 years and a total cost of almost $129 billion [4], the system was considered complete when the last traffic light was removed from I-90 as it passed through (and in some cases, over) Wallace, Idaho.

            The Interstate System produces what could be described as significant negative impacts on the environment of the United States.  Many of these impacts, however, are similar to those created by a normal road network and not a direct byproduct of the Interstate System, while some of the unique aspects of the network cause problems of their own.  Whereas more traditional roads can threaten wildlife and/or their migration patterns, two parallel roads of at least two lanes each, or one road with concrete dividers, can increase the impact that the road has on local wildlife.  The construction or transformation of a “superhighway” can also disrupt the ecology in surrounding areas, and destroy it at the point where the highway is built.  While many roads were in place prior to their designation as part of the Interstate System, very few were limited-access highways and so needed to be upgraded.  This upgrade, or in some cases, the construction of completely new roads that conformed to federal standards, added strain to ecosystems that already had experienced construction.  In some cases where the roads had been made to fit the land, the land was substantially transformed to fit new roads.

            The Interstate System also has less direct but substantial impacts on the environment.  As the road system expanded, so did accessibility, and people and development soon followed.  Much as the railroad network of the previous century had fostered the growth of new towns along its route, the Interstate System brought greater development to its surroundings, and much of that development had a negative impact on nearby environments.  In the clash between the environment and development, the Interstate System encouraged development by assisting a growing nation with its transportation needs.  Coupled with the large size of the United States and the increasing availability of means of motorized transportation, the Interstate System promoted the use of motor vehicles instead of the rail systems that many European counterparts were developing, adding to global warming with greater emissions as well as other environmental impacts of automobiles.  A new “suburban” society was only possible because of the large reliance on cars and the surge that drew populations away from downtowns on rivers of asphalt.

            While there are substantial harms from the Interstate System, the network also provides some benefits for the environment.  A number of these benefits are due to the efficient nature of the Interstate System that can reduce the environmental impact per traveler.  Because the Interstate System allows for relatively fast and steady travel with few detours and little need to slow down, automobiles can finish their journeys more rapidly and more efficiently, reducing pollution.  While this efficiency has the potential to reduce the impact on the environment, it often offsets these gains by using the excess resources saved for more transportation or other development.

            The self-enclosed nature of the Interstate System can directly aid local environments near its route as direct contact with the environment is limited to exits.  By channeling traffic between developed areas of the nation through small and efficient corridors, many undeveloped areas have reduced impacts on their environments.  Land directly alongside interstates is often preserved for environmental reasons, aesthetic reasons, or because it less desirable as real estate.  These gains, however, often come at the cost of other land that is developed as alternatives.  And even though an interstate may appear not to disturb the nearby environment with which it has little direct contact, noise pollution and its presence can disrupt ecosystems.

            The Interstate System also aids the environment by facilitating environmental protection programs that rely on the system for transportation.  Having a fast and efficient network of roads can aid the government and other agencies during natural disasters and their aftermaths.  It also encourages people to travel to national parks and other wilderness areas, supporting their existence and through them supporting the environment.  The dual mission of the national park service is to protect certain ecosystems while allowing those ecosystems to be accessed by the public, and by fulfilling their goal of public access, they are able to gather public support for supporting the environment.  By allowing greater access to preserved ecosystems, the Interstate System encourages the public to support the protection of the environment.

            The net impact on the environment is also reduced by some of the alternatives that the Interstate System provides when compared to the alternative of an ad-hoc highway network.  By providing a central system of roads, redundancies can be avoided.  Because major roads are primarily owned by the government, planning the backbone of the system in advance of need allows for greater efficiency.  It is a framework in which smaller roads can develop, and without which more and less efficient roads would exist.

            The design of the Interstate System also provides advantages over ad-hoc roads as alternatives.  It reduces the amount of mileage required to transport a certain number of vehicles, as the interstates usually have higher capacity.  In many areas where roads would meander along their routes according to the local environment, the Interstate System bypasses the local environment by removing itself from interactions with the local environment in order to be less dependent on local factors that might lengthen its route or slow down travel.  The system can even make other roads more environmentally friendly by reducing the number of cars which travel on them.  When gauging the impact of the Interstate System on the environment, these factors must be taken into consideration.

            The Interstate System is undoubtedly a boon for the American economy, but what helps the economy can often harm the environment.  The comparison between the standardized interstate network and ad-hoc highways suggests that there are many positive and negative environmental tradeoffs of the system.  As we stand at the 50-year anniversary of the creation of the Eisenhower Interstate System and evaluate its environmental legacy, we can see that it is one of mixed results.


[1] Hsieh, Yih-da Edward. (April 4, 2006). Roads-Nature’s Blight. Retrieved May 10, 2006 from

[2] US Department of Transportation: Federal Highway Administration. (2004). Chapter 2: System Characteristics. In Status of the Nation's Highways, Bridges, and Transit: 2004 Conditions and Performance.  Retrieved May 10, 2006 from

[3] Weingroff, Richard. (Jan/Feb 2006). The Year of the Interstate. Retrieved May 10, 2006 from

[4] US Department of Transportation: Federal Highway Administration. Dwight D. Eisenhower National System of Interstate and Defense Highways. Retrieved May 10, 2006 from


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