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The US Interstate System

Totalling a massive 76,640 km (47,622 miles) worth of roads, the U.S Interstate System is by far the largest main highway network on the planet – equal to roughly 2 laps around the equator. And that’s just specifically the Interstates. The total length of all roads in the country is thought to be in the region of 6.58 million kilometres (4 million miles) – that’s 8.5 return trips to the moon.   

As anybody who has ever road-tripped through the United States will know, it is the perfect country to get out for a long drive. The vast amounts of highways, roadside diners, motels and the sheer number of wonderfully bizarre oddities make it a wonderful place to put the top down, crank up the music, and enjoy the open road.  

The Interstate System completely transformed the United States, perhaps even more dramatically than the Intercontinental Railroad. What began in 1956 was proclaimed officially complete in 1992 and cost just over half a trillion dollars when adjusted for inflation. It connected distant communities and heralded the golden age of American automobile travel, but it certainly also came with plenty of negatives. From the destruction of urban communities to the devastating effect it had on public transport, the Interstate System comes with a complex legacy. 

A Star is Born

The United States is a vast country. Travelling from coast to coast is a journey of between 4,000 km and 5,600 km (2,500 and 3,500 miles) depending on your route, while a trip from the Candian border to Mexico is around 3,622 kilometres (2,250 miles). 

The Transcontinental Railroad was completed in 1869 and quickly transformed the fortunes of the country. But as the 20th Century dawned, a young pretender lay in wait. The automobile emerged in 1886 but it wasn’t until the first decade of the new century that mass production really began. In 1908, Ford’s Model T car hit the market, eventually rolling off the production line at a rate of one every 15 minutes. Though it would be a stretch to say this kind of purchase was available to everybody, it was the first time that automobiles began to filter down to the wider public. 

Ford Model T touring
Ford Model T touring by ModelTMitch is licensed under CC-BY-SA

But what good is an automobile if you’ve got nowhere to drive? At that point, the U.S road system was fairly limited – even if it hadn’t been I don’t know how confident I would have been taking a Model T on a cross-country road trip. 

First Half of the 20th Century

The automobile made quite the impression on the American public – as it did around the world. Their popularity exploded and car manufacturers could barely keep up. In 1909, Ford produced 17,771 cars, but just five years later that number reached 308,162. 

As World War I began, and with the United States still firmly neutral, talk of creating a vast interstate network was discussed for the first time. The Federal Aid Road Act of 1916 provided $75 million ($1.9 billion today) over a five-year period, which would then be matched by individual states.  

But the nation was soon pulled into conflict and plans were set aside. In 1919, the U.S Army sent a convoy of vehicles across the country to get a good idea what exactly lay in store should the nation progress with its Road Act. The Motor Transport Corps convoy took a total of 62 days to drive the 5,100 km (3,200 miles) from Washington D.C to San Francisco and left many shocked at the state of roads and bridges along the way. In Wyoming alone, they needed to repair 14 bridges, while many commented that from Illinois to Nevada was almost entirely unpaved – and very dusty.  

The convoy had a young man with them who would go on to be one of the most pivotal figures in the construction of the U.S Interstate System, a 28-year-old Dwight D Eisenhower, who commented that it had been a,  

“succession of dust, ruts, pits, and holes. The old convoy had started me thinking about good two-lane highways… the wisdom of broader ribbons across our land.” 

37 years later he would sign the Federal Aid Highway Act of 1956 as President of the United States – but that’s getting a little ahead of ourselves. 

This new love of paved highways was certainly not just down to a desire to cruise sedately through the American heartland. During World War I, the U.S government had found that its rail connections couldn’t keep up with troop and equipment deployment. They were instead forced to use roads, which as we’ve just seen were far from pristine. This was a concern seen again during the beginning of the Cold War when the threat of a nuclear attack reached fever pitch and a dedicated, high-quality road system was seen as a vital way of moving troops around the country as well as evacuating citizens from major cities if needed.  

The 20s and 30s saw large amounts of road networks added, but these were almost always in busy coastal areas – New York State, for example, added significant sections of what would eventually be the Statewide Parkway System. In 1938, President Franklin D Roosevelt set out 8 different travel corridors that wanted engineers to evaluate and it seemed like the country was inching towards a grand Interstate System – but trouble was brewing across the Atlantic. 

The Glory Years

While Europe emerged from World War II in a shattered state, the United States rose out the conflict stronger than ever. Buoyed by a booming economy and manufacturing sector, the late 40s and 50s proved to be some of, if not the, most glorious years in the nations’ history. 

Life for the middle class improved dramatically. Suddenly, everybody had TVs, refrigerators – and of course, cars, but the country still lacked its comprehensive road network system, the likes of which Germany had created before World War II – one of Adolf Hilter’s more palatable ideas.  

The automobile business was roaring but you can only sell so many cars with such a limited transportation network. Lobbyists associated with car manufacturers, oil companies, tire makers – you name it – began to actively push for changes. No doubt for the good of the nation and not because they stood to make vast amounts of money on a huge road system.  

With a few delicate nudges in the right ribs, politicians began discussing the national road system and in 1956, the Federal Aid Highway Act was brought to congress. It initially proposed a 10-year, $100 billion ($950 billion today) program that would connect all U.S urban centres with 50,000 or more inhabitants, totalling roughly 64,000 km (40,000 miles). 

Democrats initially bulked at using public bonds to finance the network, but once amendments were made which created a new Highway Trust Fund funded by a gasoline tax, most opposition dropped away. The bill was signed into law by President Eisenhower in July 1956 and initially came with a $25 billion ($237 billion today) budget over 12 years, but that would prove to be incredibly optimistic.

One year before, the ‘General Location of National System of Interstate Highways’, also known as the Yellow Book, was released by the U. S. Department of Commerce which mapped out potential routes around the country and in particular through urban centres. While plans frequently changed (and I’ll explain why later in the video) much of what was included in the Yellow Book came to fruition.   

Construction Begins

While the Act itself was only passed in 1956, some sections of what would become the Interstate System had already been constructed, and the title of the earliest section of the system is still keenly debated – but there seem to be three contenders. 

The first section of the Pennsylvania Turnpike, or as the locals like to call it the ‘Grandfather of the Interstate System’, opened back on 1st October 1940. The 261km (162 miles) stretch between Irwin and Carlisle would eventually form part of the I‑70 and I‑76 routes. 

Further west, Missouri also has a strong case and claims that the first three contracts were signed in the state on 2nd August 1956, the first of which was an upgrade to the existing Route 66, into what is now I-44. But the Missourians were quick off the mark with construction too, with work starting in St Charles County on the existing US 40, which eventually became I-70, on 13th August 1956. 

Then we have Kansas, who claim they were the first to start paving after the Act was signed into law. Preliminary work on their portion of the I-70 had already begun before the Act and it was the first completed project after it.  

As I mentioned earlier, work was not formally declared finished until 1992 and while there is far too much to tell you all about, there are certain important markers along the way. 

On 17th October 1974, Nebraska was the first state to officially complete all of its designated Interstates with the opening of its portion of the I-80 – a route that would eventually measure a 4,666 km (2,899 miles) running from the New Jersey coast across to California and the Pacific Ocean. When I-80 opened in 1986, it became the longest contiguous freeway in the world (a title it has since lost to the Pan-American Highway). Purely by accident, the point where the two sections met, and at which a dedication ceremony was held, was just 80 km (50 miles) from Promontory Point, which is where the two sections of the Transcontinental Railroad had met 117 years before. 

Another important milestone in the 1970s was the linking of America’s neighbours, Canada to the north and Mexico to the south via the 2,222 km (1,381 miles) I-5 which was officially completed on 12th October 1979. Much of this Interstate follows the historic Siskiyou Trail, a route commonly used by hunters and trappers in the 19th Century, but was itself part of a much older route used by Native Americans. 

On 14th October 1992, the Interstate System was declared finished with the completion of the tricky I-70 section near Glenwood Canyon in Colorado. This is still one of the most expensive stretches of highway anywhere in the U.S and if you’ve ever driven through it you’ll know exactly why. At just 19 km (12 miles) it isn’t particularly long, but with 40 bridges, numerous tunnels and exactly the kind of landscape you might associate with the word ‘canyons’, this section proved to be one of the most challenging of the entire system. At a final cost of $490 million (roughly $900 million today), it came out roughly 40 times the average cost per mile predicted by the planners back in the 1950s across the entire system. 

The Finished Article

There are currently 70 interstates around the United States (including sections in Alaska, Puerto Rico and Hawaii. All of these come with a single or double-digit number, there is no Interstate 1, but I-2 is in Texas and runs for 75 km (46 miles).

Then we have the 323 ‘auxiliary interstates’ which all come with a three-digit number. These are often referred to as spur routes, connecting larger routes or providing bypasses and beltways. 

States are entirely responsible for the upkeep of their Interstates and technically have control over speed limits, but after President Nixon threatened to pull funding if states didn’t comply with a 90km/h (55 mph) speed limit, everybody fell in line. This is now 115 km/h (70 mph) on most rural Interstate Highways, while in urban areas it ranges between 90 and 105 km/h (55 and 65 mph). 

A few facts that you may or may not find interesting. The longest Interstate is I-90 which connects Boston and Seattle and stretches to 4,964 km (3,085.3 miles), while the shortest primary Interstate is I-97 between Annapolis and Baltimore at just 28.3 km (17.6 miles). The busiest is the I-405 through Los Angeles which sees roughly 374,000 vehicles per day.

Public Reaction

When the Federal Aid Highway Act passed in 1956 it’s fair to say that the majority of Americans were well behind the idea – and why not? The idea of connecting urban centres with smart paved roads sounded like a wonderful idea, but it didn’t take long for the mood to change in certain areas and before long, highway revolts were being seen in states across the nation. 

The majority of these revolts came in crowded urban areas where plans for highways often severely affected local communities, sometimes cutting them in half and forcing people from their homes. If you look at urban planning maps before and after the introduction of the Interstates, it’s staggering how much land, where people once lived, was given over to the new roads.  

This was not such an issue in the rolling prairies of Kansas or Nebraska, but in congested cities, often near the coasts, and where space was at a premium, it became a real problem. San Francisco was the first place to see a major revolt against highway plans, just four years after the Act was signed. In 1959, after an extensive protest, the San Francisco Board of Supervisors voted to cancel seven of ten planned freeways – but things were just getting started. 

The 1960s saw protests in New York City, Baltimore, Washington, D.C, New Orleans and other cities across the country, leading to numerous cancellations or re-routing of proposed interstates. Even today, there are still abandoned sections that were started but never finished. 

While there were certainly many successes for protestors, the majority of Interstates were built as planned, or with only minor tweaks. But the effects on certain communities were dramatic and it forced planners and state officials to interact much closer with the local community than they had previously. It seems it was very much the case of looking at the larger picture of American progress, but not so much how this supposed progress would affect people on the ground. It goes without saying, the U.S Interstate System affected lives in vastly different ways depending on where you lived and your socio-economic status.   


The U.S Interstate System has fundamentally changed the United States with many arguing passionately for both the positives and negatives. It undoubtedly helped foster better transportation links across the country – that probably goes without saying – and opened up the nation like never before. The suburbs suddenly became much more accessible and it’s no coincidence it coincided with a surge in migration out of the cities and into the smart rows of houses that all looked roughly the same with a white picket fence in front.

However, the system also brought with it plenty of negatives, many of which are still being felt today. That middle-class migration to the suburbs was certainly not available to the whole population and poorer communities in cities often felt the brunt of construction plans. 

It also dramatically changed what it’s like to travel throughout the United States. Now, this depends somewhat on how you like your car journeys. If you want to get as fast as possible to your destination, then the Interstates are great, if you prefer to meander through quaint American towns at a sedate pace, they are awful. John Steinbeck said it well in 1962, 

“When we get these thruways across the whole country, as we will and must, it will be possible to drive from New York to California without seeing a single thing.”

Then we come to cars. There are an estimated 284 million cars in the United States today – for a population of 328 million inhabitants. The Interstate System ushered in the great American love affair with the automobile that is not going to end anytime soon. As a result of this, public transport in the country began declining in the 1950s and I don’t think many Americans will mind me saying that in certain parts of the country it is abysmal. But when everybody has a car, does it really matter? We’re not going to dive into the climate change/road congestion quagmire right now, but it’s clear that many urban areas are, or will in the future, struggle badly with the sheer numbers of cars and the limited roads. 

The Great American Highway System 

Whether you love them or hate them, the United States certainly wouldn’t be the same place without its Interstates. When adjusted for inflation, the entire system cost in the region of $530 billion and took 35 years to complete – and considering the economic benefits it’s seen as a result, that looks to be a bargain. 

In terms of global transportation projects, it was unprecedented and paved the way (pun intended) for the modern United States that we see today. But you also can’t ignore the negatives. Standing in a poor area of a city with a thundering Interstate flying over you, it’s hard to see the beauty of them. They may have led to the rise of the suburbs, but it often came at the expense of poorer communities in cities. Then there’s the frequent loss of the traditional American main street in many small towns. With strip malls often built close to the Interstates out of town, these iconic streets have seen much of their traffic diverted and have suffered horribly as a result. But this is perhaps the price you pay for progress. These built America into the powerhouse it is today. Love it or hate it, the Interstate System radically changed the United States.   

The Role of Highways in American Poverty – The Atlantic

History of the Interstate Highway System – 50th Anniversary – Interstate System – Highway History – Federal Highway Administration (dot.gov)

Interstate Highway System – Wikipedia

The Interstate Highway System – Definition, Purpose & Facts – HISTORY

The Complex History of the U.S. Interstate Highway System (interestingengineering.com)

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