On the surface, the United States Interstate Highway System, or IHS for short, may seem to be nothing but a vast series of multi-lane paved roads, median strips, overpasses, and on- and off-ramps. But this seemingly simple infrastructure is a 46,876-mile network of roads that began with a treacherous cross country roadtrip in 1919, decades of legislative battles across the states, and even helped write the story of one of America’s most famous presidents. So while paved asphalt is rarely called “exciting,” the remarkable story hidden behind America’s roads embodies a kind of understated brilliance in its sheer scale, execution, and far-reaching consequences for America.
Three lenses through which we will view the genius of the IHS in today’s video. Fasten your seatbelts and enjoy the journey! So, why is the construction of the IHS often called a “monumental undertaking?
” After all, it’s not like it was the first highway network ever built. The answer lies in its scale, engineering innovation, and economic and logistical complexity. To understand just how challenging this project was, all you need to know is that the original estimated cost of the system was $25 billion, and was expected to be constructed over a 12-year period.
The final cost ballooned to $114 billion – equivalent to $618 billion in 2023 – and took almost 30 additional years to build. Talk about a grand endeavor! To understand how the project went from $25 billion to $114 billion and from 12 years to 39 years, we must take a ride through the entire development of the IHS, from when the idea of this engineering marvel was first conceived to when construction was finally declared complete.
The earliest concept for a high-speed interstate road system dates almost as far back as the automotive industry itself – 1898. In fact, this industry is the very reason for the push toward developing efficient road networks. However, for some, this wasn’t the only reason for the project.
For Thomas MacDonald, a civil engineer and politician from Iowa, it was also personal. As a boy, MacDonald worked in his father’s grain and lumber store where he witnessed the devastating effects of poor road conditions firsthand. Specifically, farmers’ crops would rot before they could traverse the rugged roads to even reach the market, while lumber shipments would be delayed or lost due to inadequate roads.
That’s why MacDonald made it his life’s mission to bring a better life to rural communities by championing the development of a robust and efficient highway system. Fast forward to 1913, and MacDonald was appointed the chief engineer for Iowa’s newly formed highway commission. In this capacity, he worked closely with Logan Page, the Director of Public Roads, and the American Association of State Highway Officials, to secure support for the Federal Aid Road Act of 1916.
While this act was a step in the right direction, the $75 million in federal money allocated for the construction of roads was still insufficient for the ambitious vision MacDonald had in mind. However, less than a year after MacDonald’s vision was to be put into motion – along with everything the Federal Aid Road Act of 1916 stood for – all of that ceased to matter, as the U. S.
officially joined World War I. As a result, most of the resources – and attention – for the project were directed away from infrastructure development and into the war effort. Of course, this also included the work of U.
S. automobile manufacturers, who shifted their production to support military needs, leaving little room for advancements in any other area. Naturally, the situation changed once World War I came to an end.
Automobile manufacturers switched back to producing cars. And they came back in full force. Just take Ford, the leading car manufacturer in the U.
S. , as an example. During 1918, the final year of World War I, Ford produced 435,898 cars.
The next year, this figure almost doubled, reaching 820,445. That figure, incidentally, was almost four times the number of cars Ford produced in 1913, prior to the start of World War I – 202,667 cars. That figure should also indicate that car ownership in the U.
S. also skyrocketed. In 1913, there were about 1,190,000 registered passenger cars in the country.
In 1919, there were 6,679,000 of them. And yet, 90% of the U. S.
roads were still just dirt paths. However, it wasn’t until the Army Motor Transport Corps convoy explored U. S.
roads that officials truly grasped the dire state of its infrastructure. The Army Motor Transport Corps convoy was part of the 1919 Transcontinental Motor Convoys whose goal was to assess the feasibility of long-distance motor transport for military logistics purposes. This convoy departed from Washington, D.
C. – or the White House’s Ellipse, to be more precise – at 11:15 a. m.
on July 7, 1919, headed for San Francisco. By 12:30 p. m.
, the convoy crossed into Maryland but had already experienced at least two incidents with vehicles in the convoy. With every passing day, this westward expedition advanced another 40, 50, or 60 miles. On July 22, after struggling through the deep mud in Ohio and Indiana, the convoy crossed the Mississippi River at Clinton, Iowa.
Once on the western side of the river, the military personnel in the convoy quickly realized why venturing westward in a motor car was considered a ludicrous idea at the time. The rain in Nebraska made the dirt roads slippery, causing 25 trucks to slide into a ditch. Utah only brought more despair with its salt marshes that mired virtually every vehicle, requiring almost superhuman efforts to extricate them.
It was only when the convoy reached California that it once again saw pavement. After an evening in Oakland, California, the convoy was loaded onto a ferry and crossed the San Francisco Bay. Once on the other side, the convoy finally completed its journey by rolling through the streets of San Francisco on September 6, 1919, marking the end of its grueling cross-country trek.
And “grueling” might even be an understatement. If you do the math, you’ll realize that the trek from Washington, D. C.
to San Francisco took 62 days. Today, it would take roughly 42 hours. To make matters worse, the convoy used nearly all their waking hours driving.
This means that the roads at the time allowed this convoy to travel at an average speed of 5. 65 miles per hour – a torturous crawl that felt more like a slow-motion nightmare than a journey across the nation. This nightmare also retired nine of the initial 81 vehicles that set out on the journey, with their frames and wheels succumbing to the relentless strain of America’s unforgiving roads.
Out of 24 officers, 15 U. S. War Department observers, and 258 enlisted soldiers, 21 didn’t complete this journey, having been injured in the process.
These figures could’ve easily been higher since there were a staggering 230 road incidents throughout the 3,000-mile trek. Needless to say, the report submitted to Washington D. C.
was nothing short of a damning indictment of the nation’s road infrastructure. The only positive aspect is that this event served as the catalyst for creating a highway system. But believe it or not, decades would pass before any concrete steps were taken to address the flaring deficiencies exposed by the 1919 Army Motor Transport Corps convoy.
The problem was that the responsibility for constructing highways was left to individual states. And individual states had their individual interests and needs. For instance, why would Iowa build a highway to connect Illinois to Nebraska when its own infrastructure needs were pressing and local interests took precedence?
The darkest days of the Great Depression needed to happen before more comprehensive reforms addressing the nation’s road infrastructure could be implemented. In 1938, President Franklin D. Roosevelt gave MacDonald, who was now the Director of Public Roads, a hand-drawn map of the United States containing eight superhighway corridors.
The goal was clear – put people to work on building a network of roads that would not only stimulate economic growth but also unite the nation through a new era of infrastructure. The first formal description of what would become the Interstate Highway System came a year later – 1939 – at the hand of Herbert S. Fairbank, the Chief of Bureau of Public Roads Division of Information and MacDonald’s right-hand man.
This description was part of the 1939 Toll Roads and Free Roads Report, which outlined the vision and framework for a nationwide network of highways designed to transform America’s infrastructure and economy. But once again, a global war intervened. This time, World War II.
As gruesome as this war was, it inadvertently spurred plans to develop the U. S. highway system.
Remember how the 1919 Army Motor Transport Corps convoy was hell on earth for its participants but cemented the need for a national road network? Well, World War II introduced U. S.
military personnel to a highly advanced highway system that would become the inspiration for the U. S. ’s very own IHS – Germany’s autobahn network.
Interestingly, one person was present for both of these major events, using his observations to drive change later. Future President Dwight D. Eisenhower.
During the 1919 Motor Transport Corps, Eisenhower, then a lieutenant colonel, was assigned as an observer for the mission. World War II saw him assume a pivotal role as Supreme Commander of Allied Forces in Europe. During his time there, he had nothing but praise for the highway system built by Germany prior to the war.
In his presidential memoirs, he wrote, “During World War II, I had seen the superlative system of German autobahn--[the] national highways crossing that country. ” “Superlative” because this system effectively aided the Allied victory by allowing them to move troops, equipment, and supplies with unprecedented speed and efficiency. It also allowed the formation of the famed Red Ball Express, a truck convoy system that delivered vital supplies to the frontlines with remarkable speed, underscoring the crucial role of well-developed infrastructure in wartime logistics.
At its peak, the Express operated 5,958 vehicles carrying around 12,500 tons of supplies a day. So, with World War II over, the U. S.
emerged as a global superpower. Almost immediately, on November 19, 1945, Eisenhower was sworn in as the new Army Chief of Staff. Five years later, on December 19, 1950, he became the first Supreme Allied Commander for Europe at NATO.
Less than two years later, on November 4, 1952, he won the U. S. presidential election by a landslide, riding a wave of public support and promising to bring his military expertise and vision to domestic policy.
One of his priorities? Highways. Despite Eisenhower scoring career victory after victory, the U.
S. roads remained woefully inadequate. It still took substantial planning and the better part of 10 days to travel from one coast to the other.
It was clear something had to finally change. But there was one more event that would kick off the actual construction of the IHS. The 1953 detonation of the hydrogen bomb by the Soviet Union.
This event hammered home the need for change. With the detonation of the bomb, which produced a yield of 400 kilotons, the Soviet Union demonstrated that it could unleash devastating nuclear power on a scale previously unimaginable. This new reality of immense destructive capability – paired with the unstable government after Joseph Stalin’s death – underscored the need for a robust, efficient transportation network to ensure rapid mobilization, evacuation, and effective response in the event of a crisis.
After all, we’re talking about a country where 79% of people believed a nuclear war between the U. S. and the Soviet Union was imminent, which caused them to build bomb shelters, stockpile food, and prepare for the worst.
So, the Cold War – and specifically the 1953 hydrogen bomb detonation – was the third and final catalyst that propelled the U. S. into action.
In 1954, Eisenhower appointed Lieutenant General Lucius Clay, who was instrumental in the logistics success after the D-Day invasion at Normandy, the head of the President’s Advisory Committee on the National Highway System. This committee, which became known as the Clay Committee, asked for $100 billion in federal funds over 10 years – equivalent to $1. 13 trillion today – to construct a “vast system of interconnected highways.
” This ambitious plan was based on four points. No. 1 – Safety.
According to the Clay Committee, 36,000 people lose their lives annually due to inadequate roads and traffic accidents. No. 2 – The cost of vehicle ownership.
Due to poorly maintained roads, vehicle ownership and repair were becoming increasingly expensive. No. 3 – National security.
The looming nuclear threat demanded an efficient and reliable transportation network to facilitate emergency city evacuations. The committee focused on large cities and urban areas, stating, “The rapid improvement of the complete 40,000-mile interstate system, including the necessary urban connections thereto, is […] vital as a civil defense measure. ” And No.
4 – Economy. The committee emphasized that a modern highway system would be a catalyst for economic growth. In February 1955, Eisenhower forwarded this proposal to Congress, and the 1947 concept map by the Bureau of Public Records – and the dream of many Americans – was finally about to become a reality.
A year later, on June 29, 1956, Eisenhower signed the Federal-Aid Highway Act, allocating $25 billion to constructing 41,000 miles of highway. Unlike the previous 50-50 approach that failed spectacularly, the government was now responsible for providing 90% of the cost of these Interstate highways, obtaining the necessary money by hiking the federal gas tax. Interestingly, three states have laid claims on the honor of having the first interstate segments.
No. 1 – Missouri. The Missouri Highway Commission awarded the first contract to build the Interstate along the famed Route 66 in Laclede County, now designated Interstate 44.
However, the actual construction first started in St. Charles County on U. S.
Route 40. No. 2 – Kansas.
According to state officials, preliminary construction on a highway section started even before the Federal-Aid Highway Act was signed. However, it’s the finished section of Interstate 70 that the state marked as the first project completed under the provisions of the 1956 Act. And No.
3 – Pennsylvania. They claim to have the earliest completed segment of the Interstate System – the Pennsylvania Turnpike, which was once referred to as the “World’s Greatest Highway. ” A 162-mile portion of this highway, now designated Interstate 70 and Interstate 76, opened on October 1, 1940, between Irwin and Carlisle.
But where the first highways were officially opened was just an issue of state pride. What mattered on a larger scale was that a unified, efficient network of roads was finally underway. Unfortunately, this network wouldn’t be complete for decades.
By the late 1960s, only 25,000 miles of the proposed 40,000 were built. Yet, the budget was already twice as high as the 1956 estimate. However, since the would-be IHS was already proving to be a genius investment, the costs were deemed a worthwhile sacrifice for the immense benefits it promised.
In 1966, two Interstate expansions were initiated, aiming to improve trade with Canada and Mexico. Today, this Interstate, number 69, exists in several separate segments, including pieces in the following locations: Laredo, Texas Pharr, Texas Brownsville, Texas Corpus Christi, Texas Houston, Texas Northwestern Mississippi Memphis, Tennessee However, the long-term goal is to extend the highway route from Tamaulipas, Mexico, to Ontario, Canada. Interstate 11 will further enhance cross-border connectivity by bridging the gap between Phoenix, Arizona, and Las Vegas, Nevada.
In 1974, Nebraska became the first state to complete its entire portion of the Interstate system by dedicating the final piece of Interstate 80. Five years later, the final section of Interstate 5, which runs from the Canadian border to the Mexican border, was completed near Stockton, California. This highway also became the first contiguous freeway connecting these two North American countries.
Similar huge milestones kept coming in the following years. In 1986, the final section of the coast-to-coast Interstate 80 was dedicated on the western edge of Salt Lake City, Utah. With this, Interstate 80, spanning from San Francisco, California to Teaneck, New Jersey became the first contiguous freeway to connect the Atlantic to the Pacific Ocean.
At the time, it was also the longest contiguous freeway in the world. Today, at 2,900 miles, it’s the second-longest Interstate Highway in the U. S.
By the early 1990s, almost the entire 45,000 miles of IHS were complete. The last notable sections were as follows: The final section of coast-to-coast Interstate 10 from Santa Monica, California, to Jacksonville, Florida, completed on August 10, 1990 The final section of Interstate 90 from Seattle, Washington, to Boston, Massachusetts, completed on September 12, 1991 The final section of Interstate 70 passing through Glenwood Canyon in Colorado, completed on October 14, 1992 The last section, in particular, is considered an engineering marvel as it navigates the treacherous terrain of Glenwood Canyon, where little room exists for error. This challenge was overcome by building as many as 40 bridges and numerous tunnels, which made this 12.
5-mile stretch of highway one of the most expensive U. S. rural highways per mile.
At the time, the construction of this section cost $960 million, adjusted for inflation. Crunching the numbers, you’ll realize this means that a single mile of this section cost over $75 million to build. This was just one of the sections that contributed to the colossal budget allocation, which blew past the original $25 billion estimates decades before the IHS was officially concluded.
When the project started, one mile cost only $8. 5 million to construct. However, due to increasing labor costs and rising material prices, the cost per mile surged to over $34 million per mile for the simplest sections.
Even with these huge costs, protests from citizens, and other overwhelming challenges, the IHS was finally declared complete in 1992, more than two decades after Eisenhower’s death. But why do we say “declared complete” and not “completed? ” Well, because, technically, it wasn’t completed.
There were still several stretches that didn’t fully conform with the federal standards and two original Interstates – Interstate 95 and Interstate 70 – that weren’t continuous. The former finally became continuous in 2018, while the latter remains the only Interstate with a discontinuity. The reason?
There isn’t a direct interchange with the Pennsylvania Turnpike at the eastern end of the concurrency near Breezewood, Pennsylvania. Originally, funding was the issue for bridging this gap, but currently, local opposition is blocking any proposals aimed at addressing the issue. But in order to fully understand the enormous scale of the US’s largest ever infrastructure project, we need to take a closer look at the second aspect of its genius – the sheer magnitude of the finished product.
As we mentioned, the IHS is 46,876 miles long. To put this figure into perspective, all you need to know is that the inspiration behind this system – the German autobahn – is a little over 8,000 miles long. Though a few countries have longer highway systems – such as China, which has 110,000 miles of highways – the IHS remains one of the most well-connected and comprehensive highway systems in the world.
The longest Interstate within this impressive system is the east-west Interstate 90 from Boston, Massachusetts, to Seattle, Washington, measuring a little over 3,000 miles. With this length, Interstate 90 ranks among the top 25 longest highways in the world, with the first place going to Pan-American highway, spanning 19,000 miles from Prudhoe Bay, Alaska, in North America to Ushuaia, Argentina, in South America. Although we should note there is a 60 mile break in the highway at the Darien Gap, requiring the use of a ferry to continue your journey.
As for the US north-south direction, the longest highway is Interstate 95, spanning 1,908 miles from the Canadian border near Houlton, Maine to Miami, Florida. Interstate 95 also serves the highest number of states: Florida Georgia South Carolina North Carolina Virginia Washington, D. C.
Maryland Delaware Pennsylvania New Jersey New York Connecticut Rhode Island Massachusetts New Hampshire Maine Other impressive achievements of note include: New York, with the most Interstates in a single state consisting of 32 different routes Illinois, with the most primary Interstates within a single state with 13 primary highways and 11 auxiliary highways, covering nearly 2,249 miles. Texas, with the most interstate mileage within a single state, with 3,233 miles across 17 different routes As of 2022, rural Interstates account for almost 275 billion annual vehicle miles of travel, while their urban counterparts accommodate 559. 19 billion.
That’s a little over a quarter of all vehicle miles driven in the U. S. Though this figure is impressive in and of itself, it becomes even more indicative of the importance of the IHS when you consider that this system only accounts for less than 1% of the total road network in the U.
S. Speaking of the importance of the IHS, let’s look at the biggest part of its genius- the impact of this monumental system on American society. If you want to comprehend the importance of the IHS right away, you only need to hear one thing.
The IHS is arguably the best investment the U. S. has ever made.
Let’s explain why. You see, the U. S.
is the most unique country in the world in terms of the number of states it encompasses – 50, to be exact. No other country has as many states. Given the vastness and diversity of these states, an efficient, reliable, and extensive transportation network is a must.
Achieving such a system in the U. S. holds significantly more weight than building a similar network in large but less diverse nations like Australia, Brazil, Canada, China, and Russia.
Though building such a system in such a decentralized country is a success in and of itself, the consistency of the IHS elevates it to an even greater level of accomplishment. The U. S.
states might differ in governments, laws, and cultures, but their highways are (almost) all built the same. This was made possible by a simple eight-page document entitled “A Policy on Design Standards—Interstate System. ” Here’s a brief overview of some of the most important standards all Interstates should meet: No.
1 – All Interstates must have controlled access, which refers to the restriction of entry and exit points to designated interchanges, ensuring smooth and uninterrupted flow of traffic. No. 2 – There must be physical barriers or median strips between lanes of oncoming traffic to prevent collisions and enhance safety.
No. 3 – Interstates should have a minimum number of lanes, typically two in each direction, to accommodate high traffic volumes and reduce congestion. No.
4 – The design of the Interstate must include clear and consistent signage to guide drivers and ensure easy navigation across different states. The now iconic red, white, and blue shield is universally recognized as an Interstate route designator. And No.
5 – All Interstates should be built with a standard speed limit to ensure that vehicles can travel at consistent speeds, enhancing both safety and efficiency. The minimum design speed is as follows – 50 miles per hour in urban and mountainous areas and 70 miles per hour in rural areas. As for the maximum driving speed, it varies by state.
Northeastern and coastal states typically have lower limits, while the higher ones are reserved for the states west of the Mississippi River. For instance, several portions of rural Interstates 10 and 20 in Texas have a speed limit of 80 miles per hour, while the same limit generally doesn’t go above the 55-mile-per-hour mark in Washington D. C.
Thanks to these speeds – and the quality of the roads – even a transcontinental journey can now be undertaken in a matter of days. This is also the biggest advantage of the IHS for the American people – this system facilitates quick, efficient, and convenient travel. More importantly, this travel is also safer.
Thanks to wide lanes, consistent grades, and smooth turns, the IHS roads are much safer, significantly reducing the likelihood of accidents and generally providing a more reliable driving experience. When the Interstate Construction Program first began in 1956, the national fatality rate was 6. 05 deaths per 100 million vehicle miles traveled.
In 2023, it was 1. 26. The IHS has also done wonders for the U.
S. economy. Simply put, the U.
S. would’ve never have become the world’s largest economy without the powerful connectivity the IHS secured. The construction of this system virtually ushered in an entirely new segment of the economy – one that catered to travelers along the IHS.
Hotels, motels, restaurants, and service stations practically popped out of nowhere, creating a booming roadside economy. But this isn’t the only economic sector the IHS benefitted. The ease of interstate travel revolutionized several industries beyond hospitality.
Retail businesses expanded their reach to new markets, manufacturers optimized their supply chains, and distribution centers emerged to handle the increased flow of goods. The IHS also played a crucial role in facilitating commerce by connecting producers with consumers across vast distances, boosting both regional and national economies. As a result, towns like Albuquerque, Phoenix, and Dallas were able to transform into huge metropolises.
Phoenix alone grew over tenfold. In 1940, after the Great Depression ended, Phoenix had a population of about 65,000. By the 1970s, this figure rose to a staggering 874,000.
These figures shouldn’t be surprising considering the fact that the construction of the IHS had the greatest impact on the South and the West of the U. S. , as that’s where most construction took place.
In the South, Arkansas, Georgia, and South Carolina saw the most miles constructed per capita, while Montana, Nevada, Wyoming, and Utah stood out in the West. Generally speaking, the periphery of the U. S.
stood to gain the most from the IHS, as it was finally properly connected to the nation’s central hubs and markets, spurring economic growth and urban development. Even areas that seemed virtually impossible to connect saw significant improvement in accessibility. Take Interstate 70 as an example.
The construction of this Interstate is considered nothing short of an engineering marvel, as the route passes straight through the Rocky Mountains, crossing challenging terrain and reaching elevations over 11,000 feet. There’s the Eisenhower Tunnel, the highest point along the IHS with an elevation of 11,158 feet, which makes it one of the highest vehicular tunnels in the world. Then you have the Glenwood Canyon, the 12.
5-mile stretch of road that winds through a dramatic gorge, which, as we mentioned, was completed last. And finally – the San Rafael Swell, a massive area of eroded rock formations and deep canyons that the Interstate navigates masterfully. Thanks to the effort and ingenuity behind Interstate 70, the western side of the US became widely accessible for a range of developments and activities, including skiing, tourism, and commerce.
Another important role of the IHS we must mention – given that it all started with the U. S. military – is that some portions of Interstates double as emergency landing strips for military aircraft.
There are also numerous U. S. Army posts near Interstate highways, ensuring rapid deployment and logistical support in times of need.
So, for instance, the 1st Infantry Division at Fort Riley, Kansas, is close to Interstate 70, while the 3rd Infantry Division at Fort Stewart, Georgia, is positioned near U. S. Highways 17 and 84, as well as Interstate 16 and 95.
All things considered, it’s abundantly clear that the IHS has found a way to improve nearly every facet of American life, from transportation efficiency and road safety to economic development and national security. In other words, the U. S.
owes a lot to a seemingly simple collection of roads. If this video interested you, feel free to check out Why There is No Bridge Between Europe and Africa or this other video of ours, you might like. Thanks for watching, and take care out there!
