HISTORY44 - Major Cross-Country Automobile Roads

My previous blog was about the history of Flagstaff, Arizona, a city in northern Arizona that was/is a stop on numerous cross-country transportation routes, including the famous Route 66 and today’s Interstate 40.  That sparked a desire to learn more about the history of cross-country automobile roads, the subject of this blog.

 

After a short introduction, I’ll talk about the history of the little-known transcontinental Lincoln Highway, the much more well-known Route 66, and finally, the Interstate Highway System.  I’ll begin in 1912, the year America got serious, about longer distance roads.

My principal sources include “A Brief History of the Lincoln Highway,” lincolnhighwayassoc.org/history/; “The History of Route 66,” national66.org/history-of-route-66; The Interstate Highway System,” history.com/topics/us-states/interstate-highway-system; “The Complex History of the United States Interstate Highway System,” interestingengineering.com; “Future Interstate Study,” trb.org/FutureInterstateStudy.aspx; plus, numerous other online sources.

In 1912, the year the Continental United States was completed with the admission of Arizona to statehood, railroads dominated long distance and interstate transportation.  Four transcontinental railroad routes had been built in the 1880s and 1890s.  Between then and 1912, a network of connecting railways had been constructed all over America.

There were almost no good automobile roads in 1912. The relatively few miles of improved roads were only around towns and cities.  A road was “improved” if it was graded; one was lucky to have gravel or brick.  Asphalt and concrete were yet to come.   Most of the 2½ million miles of roads were just dirt: bumpy and dusty in dry weather, impassable in wet weather.  

 

A car stuck in the mud near Tama, Iowa in 1919.

Worse yet, the roads didn’t really lead anywhere.  They spread out aimlessly from the center of town. Outside cities and towns, there were almost no gas stations or even street signs, and rest stops were unheard-of.

To get from one city or town to another, it was much easier to take the train.

This was about to change.  In 1908, Henry Ford had introduced the Model T, a dependable, affordable car that soon found its way into many American households. By 1912, there were an increasing number of both automobiles and drivers - with places to go.

Lincoln Highway

In the early 1900s, before a nationwide network of numbered highways was adopted by the states, an informal network of privately-funded auto trails existed in the United States.  Marked with colored bands on utility poles, the trails were intended to help travelers in the early days of the automobile.

Another assist to drivers in the early 1900s were roadmaps.  The first truly useful motorist guidebook emerged in 1901, with maps covering Boston, New York, Philadelphia, Washington, and Baltimore.  These first roadmaps didn’t contain every road.  Instead, there was a list of instructions guiding drivers from one place to another using mileage between towns, mileage between each instruction, and local landmarks.  It might say at mile 58.5, “left-hand turn just before railroad,” or “turn right away from poles.”  The book included stops where drivers could find gasoline, lubricants, or repair shops, or a place to charge their electric vehicles.  (See my March 27, 2021 blog, “The Promise of Electric Vehicles.”)  The guide’s popularity increased significantly in 1906, when AAA became its official sponsor, and expanded to 10 volumes covering most of the country the following year.

But the guide had its competitors.  In 1904, mapmaker Rand McNally printed its first automobile road map of New York City and vicinity.  Three years later, the company undertook publication of the Photo-Auto Guides from Gardner Chapin.  The guide combined maps and photos with arrows to indicate turns. In 1915, cartographer George Coupland Thomas developed a unique page-by-page grid system of mapping that eliminated the need for a folding map.  McNally loved it.  By 1924, Rand McNally’s Auto Chum appears, the first edition of what becomes Rand McNally Road Atlas.

The Vision.  In 1912, Carl Fisher, an early automobile enthusiast who had been a racer, the manufacturer of Prest-O-Lite compressed carbide-gas headlights used on most early motorcars, and the builder of the Indianapolis Speedway, proposed a graveled highway spanning the continent from coast to coast.

 

Carl Fisher, builder of the Indianapolis Speedway, conceived and helped develop the Lincoln Highway.

Communities along the route would provide the road building equipment and in return would receive free materials and recognition as a place along America’s first transcontinental highway.

To fund this scheme, Fisher received cash donations from auto manufacturers and accessory companies. The public could become members of the highway organization for $5 (about $28 dollars today).

Henry Joy, president of the Packard Motor Car Company, wholeheartedly supported the project and became the primary spokesman for the highway.  He came up with the idea of naming the highway after Abraham Lincoln.

Implementation.  On July 1, 1913, a group of automobile enthusiasts and industry officials established the Lincoln Highway Association (LHA) "to procure the establishment of a continuous improved highway from the Atlantic to the Pacific, open to lawful traffic of all description without toll charges."  Henry Joy was elected as president. Carl Fisher, was elected vice-president.

The LHA had two goals.  One goal was to build a "Coast-to-Coast Rock Highway" from Times Square in New York City to Lincoln Park in San Francisco. The second goal was to make the Lincoln Highway an object lesson that would, in the words of its creator, Carl G. Fisher, "stimulate as nothing else could the building of enduring highways everywhere that will not only be a credit to the American people but that will also mean much to American agriculture and American commerce."  The LHA's founders wanted the shortest, most direct route possible between the two points.  The route did not deviate from a straight path in order to go through larger cities or national parks.  That initial road was 3,389 miles long.  Less than half of it, 1,598 miles, was improved. (Eventually, as segments of the route were improved, the length shrunk to about 3,140 miles.)

 

The route of the Lincoln Highway, including a northern and southern route option in California around the Sierra Nevada Mountains.

The LHA dedicated the route of the Lincoln Highway on October 31, 1913.

At a time when a service infrastructure to support the automobile did not exist, motorists were urged to buy gasoline at every opportunity, no matter how little had been used since the last purchase.

For the most part, the LHA used contributions for publicity and promotion to encourage travel over the Lincoln Highway, as well as to encourage state, county, and municipal officials to improve the road. The LHA did, however, help finance construction of short sections of the route.

One of the Lincoln Highway's greatest contributions to future highway development occurred in 1919, when the U.S. Army undertook its first transcontinental motor convoy, taking 62 days on the road from Washington D.C. to Oakland, California. The convoy suffered many setbacks and problems on the route, such as poor-quality bridges, broken crankshafts, and engines clogged with desert sand.  One participant in the convoy was young Army officer, Lt. Colonel Dwight David Eisenhower.  That difficult experience, plus his observations of the efficient German Autobahn network during World War II, convinced him to support construction of the Interstate Highway System when he became President.

By the mid-1920s, the Nation was crisscrossed by a network of approximately 250 mostly unimproved named trails. Some were major intercontinental routes, such as the Lincoln Highway; the National Old Trails Road, between Baltimore, Maryland and Los Angeles, California; the Old Spanish Trail, between St. Augustine, Florida and San Diego, California; and the Jefferson Highway, between Winnipeg, Manitoba and New Orleans, Louisiana.  But most named trails were shorter. They had become a confusing tangle, often on routes selected more because of the willingness of local groups to pay "dues" to a trail association than because of transportation value. Some of the trail organizations were fly-by-night groups that were more interested in "dues" than road.  Sometimes, where several named highways shared a route, almost an entire pole would be striped in various colors.

Also, by the mid-1920s, the Ford company had sold nearly 15 million cars.  Ford’s competitors had followed its lead and begun building cars for everyday people. “Automobiling” was no longer an adventure or a luxury: It was a necessity.

A nation of drivers needed good roads, but building good roads was expensive. Who would pay the bill?  Automobile interests - such as car companies, tire manufacturers, gas station owners, and suburban developers - needed to convince national, state and local governments that roads were a public concern.  That way, they could get the infrastructure they needed without spending any of their own money.

National Highway System.  In 1925, federal and state officials established the Joint Board on Interstate Highways to plan for interstate highway construction. The plan also created the U.S. Numbered Highway System to replace the old trail designations.  All named roads were ignored in their planning.  The Secretary of Agriculture approved the plan, which set up the now-familiar U.S. highway system.  The Federal Government was the coordinating agency, with most of the funding for highway construction provided by state and local governments.

Generally, east-to-west highways were even-numbered, with the lowest numbers in the north, and the highest in the south.  North-to-south highways were typically odd-numbered, with the lowest numbers in the east and the highest in the west.  Major east-west routes usually had numbers ending in "0,” while major north-south routes generally had numbers ending in "1" or "5.”  Three-digit numbered highways were generally spur routes of parent highways. (These guidelines were not rigidly followed, and many exceptions exist.)

The Lincoln Highway was broken up into U.S. 1, U.S. 30, U.S. 530, U.S. 40, and U.S. 50.  Nearly two-thirds of the Lincoln Highway’s length was designated as U.S. 30. The Nation also adopted a standard set of road signs and markers, and to avoid confusion, all markers of all named roads were taken down.

 

The Lincoln Highway was broken up into these numbered highways.

The States approved the U.S. numbering system in November 1926 and began putting up the newly approved signs.

Legacy.  The Lincoln Highway was the Nation's premier highway, but it never quite measured up to the dreams of its founders; it was never quite finished.  But its success helped the country achieve the LHA's goal of enduring highways everywhere.

While the other named highways were quickly forgotten, the Lincoln Highway was not.  A whole generation of Americans, exposed to the well-organized publicity of the Lincoln Highway Association, kept the Lincoln Highway alive long after its official significance was gone.

Route 66

The original inspiration for an improved roadway between Chicago and Los Angeles came from entrepreneurs Cyrus Avery of Tulsa, Oklahoma, and John Woodruff of Springfield, Missouri. The pair lobbied the American Association of State Highway Officials (AASHO) for the creation of a route following the 1925 plans.

 

Entrepreneur Cyrus Avery of Tulsa, Oklahoma, lobbied for an improved highway between Chicago and Los Angeles.

 

Planning.  Officially, the numerical designation 66 was assigned to the Chicago-to-Los Angeles route in the summer of 1926. With that designation came its acknowledgment as one of the nation’s principal east-west arteries.

From the outset, public road planners intended U.S. 66 to connect the main streets of rural and urban communities along its course for the most practical of reasons: most small towns had no prior access to a major national thoroughfare.

Route 66 did not follow a traditionally linear course.  Its diagonal course linked hundreds of predominantly rural communities in Illinois, Missouri, and Kansas to Chicago, thus enabling farmers to transport grain and produce for redistribution. The diagonal configuration of Route 66 was particularly significant to the trucking industry, which by 1930 had come to rival the railroad for preeminence in the American shipping industry. The route between Chicago and the Pacific coast traversed essentially flat prairie lands and enjoyed a more temperate climate than northern highways, which made it especially appealing to truckers.

The path of Route 66 between Chicago and Los Angeles.

 

Implementation and Place in Americana.  Cyrus Avery called for the establishment of the U.S. Highway 66 Association to promote the complete paving of the highway from end to end, and to promote travel along the highway.  In 1927, in Tulsa, Oklahoma, the Association was officially established with John Woodruff elected the first president.

Much of the early highway, like all the other early highways, was gravel or graded dirt.  During its nearly 60-year existence, U.S. 66 was under constant change. As highway engineering became more sophisticated, engineers constantly sought more direct routes between cities and towns.  Many sections of U.S. 66 underwent major realignments.

The Dust Bowl of the 1930s, a period of extreme drought and dust storms in the Plains states, saw many farming families, mainly from Oklahoma, Arkansas, Kansas, and Texas, heading west on Route 66 for agricultural jobs in California.  In his famous social commentary, The Grapes of Wrath, John Steinbeck proclaimed U.S. Highway 66 the “Mother Road.”  Steinbeck’s classic 1939 novel, combined with the 1940 film recreation of the epic odyssey, served to immortalize Route 66 in the American consciousness.  An estimated 210,000 people migrated to California to escape the despair of the Dust Bowl.  Certainly, in the minds of those who endured that particularly painful experience, and in the view of generations of children to whom they recounted their story, Route 66 symbolized the “road to opportunity.”

During the Great Depression, Route 66 gave some relief to communities located on the highway. The route passed through numerous small towns and, with the growing traffic on the highway, helped create the rise of mom-and-pop businesses, such as service stations, restaurants, and motor courts, all readily accessible to passing motorists.

From 1933 to 1938, thousands of unemployed male youths from virtually every state were put to work as laborers on road gangs to pave the final stretches of the road.  As a result of this monumental effort, the Chicago-to-Los Angeles highway was reported as “continuously paved” in 1938, the first U.S. highway to be completely paved - at a total length of 2,448 miles.

Completion of this all-weather capability on the eve of World War II was particularly significant to the Nation’s war effort.  At the outset of American involvement in World War II, the War Department singled out the West as ideal for military training bases, in part because of its geographic isolation, and especially because it offered consistently dry weather for air and field maneuvers.

During World War II, additional migration westward occurred because of war-related industries in California.  U.S. 66, already popular and fully paved, became one of the main routes, and also served for moving military equipment.

After World War II, in the 1950s, Route 66 became the main highway for vacationers heading to Los Angeles. The road passed through the Painted Desert and near the Grand Canyon.  Meteor Crater in Arizona was another popular stop.

Store owners, motel managers, and gas station attendants recognized early on that even the poorest travelers required food, automobile maintenance, and adequate lodging. Just as New Deal work relief programs provided employment with the construction and the maintenance of Route 66, the appearance of countless tourist courts, garages, and diners promised sustained economic growth after the road’s completion. If military use of the highway during wartime ensured the early success of roadside businesses, the demands of the new tourism industry in the postwar decades gave rise to modern facilities that guaranteed long-term prosperity.

Tourism along Route 66 spawned the building of all sorts of motels, such as this iconic Wigwam Village in Holbrook, Arizona.

 

One such traveler was Bobby Troup, former pianist with the Tommy Dorsey band and ex-Marine captain.  He penned a lyrical road map of the now famous cross-country road in which the words, “get your kicks on Route 66” became a catch phrase for countless motorists who moved back and forth between Chicago and the Pacific Coast. The popular recording was released in 1946 by Nat King Cole, one week after Troup’s arrival in Los Angeles.

Route 66 and many points of interest along the way were familiar landmarks by the time a new generation of postwar motorists hit the road in the 1960s.  It was during this period that the television series, “Route 66,” starring Martin Milner and George Maharis, drove into the living rooms of America every Friday.  The TV series brought Americans back to the route looking for new adventure.

Martin Milner and George Maharis starred in the Route 66 television series in 1960-1963.

 

Excessive truck use during World War II, and the comeback of the automobile industry immediately following the war, brought great pressure to bear on America’s highways. The National Highway System had deteriorated to an appalling condition. Virtually all roads were functionally obsolete and dangerous because of narrow pavements and antiquated structural features that reduced carrying capacity.

The Interstate Highway System.  The beginning of the decline for U.S. 66 came in 1956 with the signing of the Interstate Highway Act by President Dwight D. Eisenhower. The legislation provided a comprehensive financial umbrella to underwrite the cost of the National Interstate and Defense Highway System.

At the time, the U.S. Numbered Highway System was a dense network of roads crisscrossing the entire country, and had reached a total length of almost 158,000 miles.

The outdated, poorly maintained vestiges of U.S. Highway 66 completely succumbed to the interstate system.  By 1970, nearly all segments of the original Route 66 were bypassed by a modern four-lane highway.  In October 1984, the final section of the original road was bypassed by Interstate 40 at Williams, Arizona.

With the decommissioning of U.S. 66, no single interstate route was designated to replace it, with the route being covered by Interstate 55 from Chicago to St. Louis, Interstate 44 from St. Louis to Oklahoma City, Interstate 40 from Oklahoma City to Barstow, Interstate 15 from Barstow to San Bernardino, and a combination of California State Route 66, Interstate 210, and State Route 2 or Interstate 10, from San Bernardino across the Los Angeles metropolitan area to Santa Monica.

Legacy.  When the highway was decommissioned, sections of the road were disposed of in various ways.  Within many cities, the route became a "business loop" for the interstate. Some sections became state roads, local roads, private drives, or were abandoned completely.  Although it is no longer possible to drive U.S. 66 uninterrupted all the way from Chicago to Los Angeles, much of the original route and alternate alignments are still drivable with careful planning. 

Some states have kept the “66” designation for parts of the highway, albeit as state roads. In Missouri, Routes 366, 266, and 66 are all original sections of the highway.  State Highway 66 in Oklahoma remains as the alternate "free" route near its turnpikes.  "Historic Route 66" runs for a significant distance in and near Flagstaff, Arizona.  Farther west, a long segment of U.S. 66 in Arizona runs significantly north of Interstate 40, and much of it is designated as State Route 66.

On old Route 66 in Winslow, Arizona, there is park named “Standin’ in the Corner Park,” that commemorates the song, “Take it Easy,” recorded by the Eagles in 1972.  The song includes the verse, “Well, I’m standin’ on a corner in Winslow, Arizona and such a fine sight to see.  It’s a girl, my Lord, in a flatbed Ford slowin’ down to take a look at me.”  The Park was developed to spark a renaissance of Winslow after Interstate 40 bypassed the community.

 

In August 2021, Pat and I visited Standin' on the Corner Park in Winslow, Arizona.

Various sections of the Route 66 have been placed on the National Register of Historic Places.

Many preservation groups have tried to save and even landmark the old motels and neon signs along the road in some states.

In 1999, President Bill Clinton signed a National Route 66 Preservation Bill that provided for $10 million in matching fund grants for preserving and restoring the historic features along the route.

In 2008, the World Monuments Fund added U.S. 66 to the World Monuments Watch as sites along the route such as gas stations, motels, cafés, trading posts, and drive-in movie theaters are threatened by development in urban areas and by abandonment and decay in rural areas. The National Park Service developed a Route 66 Discover Our Shared Heritage Travel Itinerary describing over one hundred individual historic sites.  As the popularity and mythical stature of U.S. 66 has continued to grow, demands have begun to mount to improve signage, return U.S. 66 to road atlases, and revive its status as a continuous routing.

Route 66 symbolized the renewed spirit of optimism that pervaded the country after economic catastrophe and global war. Often called, “The Main Street of America,” it linked a remote and under-populated region with two vital 20^th century cities - Chicago and Los Angeles.

Interstate Highway System

After he became U.S. President in January 1953, Dwight Eisenhower appointed General Lucius D. Clay to investigate the need for an interstate highway system.  Clay stated that, it was evident we needed better highways for safety, to accommodate more automobiles, and defense purposes, if that should ever be necessary.   He also noted that we also needed them for the economy, not just as a public works measure, but for future growth.

General Clay came up with a plan to build 40,000 miles of divided highways that would link all of America's cities having a population of 50,000 or greater.

Construction.  With the passage of the Federal Aid Highway Act of 1956, construction got underway of the Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System (IHS).

 

President Dwight Eisenhower signed off on the Interstate Highway System in 1956.

Each interstate highway was required to be a controlled-access highway with at least four lanes, and no at-grade (same level) crossings.  Controlled-access highways would have on- and off-ramps, and were designed for high-speed traffic.  While some older freeways were adopted into the system, most of the routes were completely new construction, greatly expanding the freeway network in the U.S.

Missouri was first state off the block, when on August 13, 1956, work began in St. Charles County on U.S.-40, which is now named I-70.  The Interstate Highway System was considered finished on October 14, 1992 with the completion of I-70 through Glenwood Canyon in Colorado; it is considered to be an engineering marvel with a 12-mile span containing 40 bridges and numerous tunnels.

In 1966, the Interstate Highway System was designated as part of the Pan-American Highway System, linking Canada, the U.S. and Mexico.

The complete U.S. Interstate Highway System 2018.

 

Some of these new freeways, especially in densely populated urban areas, were controversial, as their building necessitated the destruction of many older, well-established neighborhoods.  There were many “freeway revolts” during the 1960s and 1970s, including in such metropolitan areas as the District of Columbia, Indianapolis, Baltimore, New York City, San Francisco, and Boston.  Several planned interstates were abandoned or re-routed to avoid urban cores.

Though much of their construction was funded by the federal government, interstate highways are owned by the state in which they were built.

About 70% of the construction and maintenance costs of interstate highways in the United States have been paid through user fees, primarily the fuel taxes collected by the federal, state, and local governments. To a much lesser extent, they have been paid for by tolls collected on toll highways and bridges. The rest of the costs of these highways are borne by general fund receipts, bond issues, designated property taxes, and other taxes.

Toll Roads.  Federal legislation initially banned the collection of tolls, but some of the new interstate routes became toll roads, either because they were grandfathered into the system, or because subsequent legislation allowed for tolling of interstates in some cases. 

Some large sections of interstate highways that were planned or constructed before 1956 are still operated as toll roads, for example the Massachusetts Turnpike (I-90), the New York State Thruway (I-87 and I-90), and the Kansas Turnpike (I-35, I-335, I-470, I-70).  Others have had their construction bonds paid off and they have become toll-free, such as the Connecticut Turnpike (I‑95), the Richmond-Petersburg Turnpike in Virginia (also I‑95), and the Kentucky Turnpike (I‑65).  About 2,900 miles of toll roads are included in the Interstate Highway System today.

Numbering System.  The Interstate Highway System utilizes a numbering system whereby primary roads have one- or two-digit numbers, and shorter routes have three-digit numbers, with the last two digits matching the parent route. For example, I-787 in Albany, New York is a short spur that attaches to I-87.  Major arteries that span long distances were assigned numbers that are divisible by five.  East-west highways are even-numbered, while north-south highways are odd-numbered.  Even-numbered routes increase going from south to north, and odd-numbered routes increase when going from west to east (opposite of original Numbered Highway System). For example, north-south I-5 runs between Canada and Mexico along the West Coast, while I-95, which spans between Canada and Miami, Florida, runs along the East Coast.  West-east arteries include I-10, which spans between Santa Monica, California, and Jacksonville, Florida, and I-90, which runs between Seattle, Washington, and Boston, Massachusetts.  There are no "I-50" and "I-60" because other U.S. highways currently use those numbers.

 

Odd and even IHS numbering system.

The Interstate Highway System extends to Alaska, Hawaii, and Puerto Rico.  In Hawaii, the interstates are all located on the Island of Oahu, and they all have the prefix "H". For example, there are H-1, H-2, H-3, and H-201.  

Interstates in Alaska and Puerto Rico are numbered sequentially in the order of their funding, and they have the prefixes "A" and "PR", respectively. 

For one- or two-digit interstates, mile marker numbering begins at their southern- or western-most points. If an interstate originates within a state, then mile marker numbering starts at the southern or western state line.

Exit numbers of interstates are either sequential, or else distance-based, so that the exit number is the same as the nearest mile marker. For locations having multiple exits within the same mile, exit numbers are assigned letter suffixes.

Business loops or spurs are routes that intersect an interstate and go through a city's central business district.  A city may have more than one business loop.  Business loop signs are green shields which differ from the regular Interstate Highway System's red and blue shields.

 

IHS regular and business loop shields.

 

Currently, speed limits on interstates are set by the individual states and range from 50-80 mph, depending on whether or not the road is in open country or in a sharp-turn urban environment.

IHS Impacts.  The Interstate Highway System's impact on the U.S. has been enormous. It caused a sharp decline in both railway shipping and passenger traffic, while at the same time, the trucking industry expanded. This caused a drop in the cost of shipping goods. 

The Interstate Highway System is responsible for the explosive grown of suburbs during the late 1950s and 1960s. The new roadways linked suburban homes to jobs located in the cities.

The IHS also is also responsible for the "road trip,” where entire families packed into the car and hit the road. This, in turn, led to the creation of visitor attractions, service stations, motels, and restaurants.

The Interstate Highway System has been blamed for the decline of cities not on the highway's grid, and for the decay of urban centers.

As one of the components of the National Highway System, interstate highways improve the mobility of military troops to and from airports, seaports, rail terminals, and other military bases.

The IHS has also been used to facilitate evacuations in the face of hurricanes and other natural disasters.  An option for maximizing traffic throughput on a highway is to reverse the flow of traffic on one side of a divider so that all lanes become outbound lanes. This procedure, known as contraflow lane reversal, has been employed several times for hurricane evacuations.

Statistics.  In 2020, there were about 290 million cars on U.S. roads.

About one-quarter of all vehicle miles driven in the country used the Interstate Highway System.

Today, the IHS is comprised of 48,440 miles of roadway. It was initially estimated to cost $25 billion and take 12 years to complete.  It actually ended up costing $114 billion ($530 billion in 2019 dollars) and took 35 years to complete.

 

Typical interstate highway in open country.

Some additional statistics:  The heaviest traveled interstate is I-405 in Los Angles California at 374,000 vehicles per day.  The highest elevation interstate is I-70 in the Eisenhower Tunnel at the Continental Divide in the Colorado Rocky Mountains.  The longest east-west interstate, at 3,020 miles, is I-90 from Boston, Massachusetts to Seattle, Washington.  The longest north-south interstate, at 1,908 miles, is I-95 from the Canadian border, near Houlton, Maine to Miami, Florida.  With 26 lanes in certain parts, the Katy Freeway, or Interstate 10, is the widest highway in the world. It serves more than 219,000 vehicles daily in Houston, Texas.

Future of Interstate Highway System.  The IHS has continued to expand and grow as additional federal funding has provided for new routes to be added, and the system will grow into the future.

But, today, the Interstate Highway System is facing a perfect storm - while it continues to be a vital mobility network for the Nation, it risks degradation and obsolescence from aging and excessive wear, and difficulty accommodating new vehicle technologies.

Many Interstate highway segments are more than 50 years old and subject to much heavier traffic than anticipated. They are operating well beyond their design life, made worse by lack of major upgrades or reconstruction. They also are poorly equipped to accommodate even modest projections of future traffic growth, much less the magnitude of growth experienced over the past 50 years.

 

Example of a complex urban intersection of interstate highways today.

Not only did the U.S. fail to invest appropriately in the past, funding for the next 20 years is facing a fast-closing window. This 20-year period coincides with the entire system reaching the end of its design life. At the same time, it overlaps with the onset of automated, electric, and connected (to the internet) vehicles.

Congress directed the Transportation Research Board (TRB), a program unit of the National Academies of Sciences, Engineering, and Medicine, to form a special committee to conduct a study to inform pending and future federal investment and policy decisions concerning the Interstate Highway System.

The Board’s recommendations include creating a federal program dedicated to renew and modernize interstate highways over the next 20 years; raising additional funds by increasing the federal fuels tax, allowing states and metro areas to toll more interstates, and possibly adopting mileage-based use fees; and planning for the transition to electric, automated, and connected vehicles.