9 Things You May Not Know About the U.S. Interstate Highways

Last Christmas some 85.8 million people were expected to drive more than fifty miles from their homes. With gas prices falling and the weather across much of the U.S. tolerable, we can only expect that number to rise this year. Last Christmas, nearly 30 percent of those people took a trip with one in four taking a road trip. And there is one thing all these drivers had in common: At one point or another, they all utilized the U.S.’s vast Interstate Highway system.

“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.” 

—John Steinbeck, Travels With Charley: In Search of America

Here are 9 facts to annoy your fellow travelers with….

1. The Highways Weren’t Eisenhower’s Idea

Eisenhower gets quite a bit of credit for the Interstate Highway system, but he was far from the first leader to push for a nationwide, limited access motorway–fancy way of saying Interstate. In reality, the U.S. had already kicked the tires as it were on a freeway system as early as 1939. Congress debated the construction of a system of interlinking toll and free roads, but nothing came of it. In 1944, Congress passed the Federal-Aid Highway Act, but it never established funding or construction means. That would not come until the Federal-Aid Highway Act of 1956 that Eisenhower signed.

Köln-Bonn Autobahn 1932, with overpass allowing for clear, free traffic

Köln-Bonn Autobahn 1932, with overpass allowing for clear, free traffic

While it is true that Eisenhower got the highway bug in his system while rolling along with the U.S. Army toward Berlin on wonderfully wide roads that Adolf Hitler had built. Though Hitler is widely credited as the first freeway builder–the German Autobahns–this is also wrong. That title belongs to Hitler’s partner in crime, Benito Mussolini. Italy’s 80-mile long autostrada connecting Milan to Verese, designed by Piero Puricelli, was the world’s first limited-access motorway and opened in 1924. This beat Germany’s Köln-Bonn Autobahn by five years.

2. The “Semi”

The true paladins of the open road, truckers are either the bane of automobile drivers–clogging the highways by trying to pass other trucks–or white knights who rescue stranded drivers along desolate stretches of American wastelands. One thing is for sure, truckers and their rigs are an integral cog in the mechanisms of American economics.

National Lampoon's Christmas Vacation

National Lampoon’s Christmas Vacation

As you cruise down the highway toward Grandma’s house, just accept the fact that you will not be able to avoid the semi trailers careening down the road. There are close to 5.6 million of them registered in the U.S. And it is from these trailers that the “semi” truck got its name. These trailers are called semi trailers because they lack any front wheels and must be pulled. The term semi truck evolved from that.

As to the other “semi”, a Harris Interactive poll found that of the 1,832 U.S. adults who participated in the survey 11% admitted to “having participated in a sexual activity while driving.” So, if you find yourself working more than one stick on the highway, remember two things: 1. You’re not the first and, 2. Truckers in their semi’s have a prime perch for watching it all.

3. Non-Interstate Interstates

By definition, interstate means “existing between or including different states”. This makes perfect sense for anyone driving I-10 from California to Florida, but what is the deal with Interstates H-1, H-2, and H-3 in Hawaii?

Interstates H-1 and H-3 in Hawaii

Interstates H-1 and H-3 in Hawaii

How can there be “Interstates” in a state with no possible border to another state? In order for Hawaii to truly have interstates there would need to be a bridge nearly 2,400 miles long to connect it to San Francisco. For perspective, that would be a bridge nearly the length of I-10. What gives Hawaii?

Turns out Hawaii’s statehood movement had a lot to do with their getting Interstates. When the first interstates were being constructed, they had to meet a number of criteria including: Aid to national defense, whether the road is integral as a connector for population centers, service to industry (links to factories, mining, fishing, forestry, agriculture), and population. Hawaii gained statehood in the midst of this frenzied road building and the Federal Government enacted a study to decide if there was a need in Hawaii based on the criteria used for all the other roads. In 1960, a 50-mile system was recommended. And so, Hawaii got its Federal Interstate Highway system. They were given the “H” designation to set them apart from the primary Interstate system

As a side note: Alaska and Puerto Rico also have Federal Interstate Highways though they also are not contiguous to the main 48. Alaska’s highways are designated A 1-4 and Puerto Rico’s are designated PRI 1-3.

Second note: Not all of the interstates in the main 48 are true interstates, either. Several, including I-97 in Maryland, I-73 in North Carolina, and I-19 in Arizona, do not leave their states. It all comes down to where they got their funding.

4. Numbering the Roads and The Missing Interstates

Unlike nearly everything else the government does, there is actually a rhyme and reason to the numbering of the U.S. Interstates.  And this is one of the rare times where government intervention actually did something good.

Prior to the Federal Interstate Highway system, the United States was criss-crossed by roads built by for profit groups. During the 1920s many of these roads could barely be called roads as they were more mud, dirt and ditches than road. But, as Henry Ford continued to churn out automobiles, more and more of these state highways popped up across the landscape. Most of these roads followed old trails or Transcontinental Trails like the Oregon and Santa Fe. One of the first transcontinental highways was the Lincoln Highway from New York to San Francisco. It was a rock road and privately financed; Henry Ford wanted nothing to do with it because he thought roads and highways should be funded by the government. As the 1920s progress other groups formed to build and promote their own highways. By 1925, there were over 250 named highways, each with their own colored signs, names, and random sign placement. Without government oversight, many of these roads were re-routed into cities so that the clubs and groups that built them could profit from them.

Lincoln Highway between Fernley and Hazen, Nevada

Lincoln Highway between Fernley and Hazen, Nevada

In the midst of this chaos, the Federal government got involved in 1924 and started numbering all of these roads. Odd numbers ran North to South with the numbers increasing from East to West, and Even numbers run East to West with the numbers increasing from North to South. So, U.S. Route 1 runs along the Eastern Seaboard while U.S. Route 10 runs along the Canadian border.

When the Interstate Highways came along, the government decided to use the mirror image of the numbering system to avoid any confusion. Interstate 10 runs through the southern states while I-5 is in California. Thankfully, the government was wise enough to help avoid the classic “How could you get us lost?” fight between drivers and map readers. Where the two systems, the routes and the Interstates, meet in the middle of the country it was decided that there would be no Interstate 50 to avoid confusion with U.S. Route 50 which runs from Sacramento, CA to Ocean City, MD. This is the same for Interstate 60.

5. #1, #2, A Walk, And A Stretch, But No Food

For many Americans, a road trip means getting from point A to point B. In my house, my father’s mantra was: “The gas tank is full and our bladders are empty. We drive until the opposite is true.” This meant that I got to miss the many wonderful, and some not so wonderful, road side rest stops along the way.

The idea of a road side park predates the Interstate. Allen Williams, county engineer with the Ionia, MI County Roads Commission, is often credited with creating the road side stop.  In the late 1920s, he saw a young family trying to enjoy a picnic lunch along side the road, but they were sitting in the dirt with their food on a tree stump. A short while later, Williams put up a couple picnic tables he and his road crew had constructed along Route 16 just outside Saranac.

Rest Area sign on I-80 in Nevada

Rest Area sign on I-80 in Nevada

The Safety Rest Area as we know them grew as the Interstates were built with the first ones constructed in the late 1950s. One thing that has stayed constant with the Rest Areas–other than the smell–is that there is no food for sale at any of them. During the passage of the Federal-Aid Highway Act there was some debate as to allow commercial sales at the Rest Areas. However, House Representative Charles A. Vanik (D-OH) made clear Congress’ goals for the highways and their rest areas when he said, “Let the highway traveler turn off the Interstate system if he requires food, motor-vehicle service, lodging or Stuckey’s pecans.” This was done so that the small towns along the way wouldn’t lose out on customers. The safety areas are solely so the driver can get out, stretch, shake off drowsiness, take care of #1 and #2, and get right back on the road. In 1982, the law was amended a bit to allow for vending machines, however, in rural or remote parts of the country the rest areas are without so pack a lunch.

6. You Can’t Get There From Here

There are some places that the Interstate just can’t take you. And I don’t mean some small little village in the middle of the corn in Iowa. There are four state capitals that are not served by the Interstate system. You cannot get to Juneau, Alaska; Dover, Delaware; Jefferson City, Missouri; or Pierre, South Dakota on an interstate. Some internet trivia sites will list five state capitals, but the fifth, Carson City, Nevada, has recently been linked to the interstate system by I-580 running from Carson City to Reno (and I-80). And, it also happens that I-580 is yet another non-interstate interstate.

Eisenhower National Highway System

Eisenhower National Highway System

It isn’t just state capitals that the interstates avoid. There are some pretty large cities that are not served by the interstate system. Of the top 10, nine are in California including: Fresno (#37 on the 2000 census; cities with 100,000+ population), Bakersfield (#68), and Modesto (#101). Brownsville, TX (#150) comes in as the seventh largest city not served.

If you happen to live near an interstate and want to get away there are some pretty remote places that let you escape the noise, pollution, and trash. Your first option would be Barrow, Alaska. There are NO roads to Barrow. The nearest road would be in Prudhoe Bay and that is 197 miles. The nearest interstate would be in Fairbanks over 500 miles away… by plane. If that is too extreme, you could chose Morgan, MT 183 miles in a direct line away from I-15. Earl Swift, author of Big Roads, chose this hamlet of a few houses and white-tailed deer as the place furthest from the interstate. However, if you want to have neighbors, you might choose Whitewater, MT with a population of 64 (2010 census) and 175 miles from I-95. Tonopah, NV (150 miles as the crow flies from I-80) has a population of 2,478 (2010 census). Based on driving distance Key West, Florida (pop. 24,649 in 2010) is 162 miles from I-95 in Miami. And, it is a tropical paradise to boot!

7. Landing Strips and Curvy Bends?

While these might be popular in a Victoria’s Secret fashion show, that they are purposely built into the National Highway System is false. These two items–highways as runways and curves for monotony–are the most widely perpetuated myths of the entire Interstate System. (Just an FYI–Googling “landing strip” is definitely NSFW, especially an image search).

Let’s look at the first myth: Every ____ number of miles has to be straight to use as a runway in time of war. Proponents of this myth use Eisenhower and the Autobahn as their source, and, as with every myth, there is a bit of truth in the story. The German Autobahn was designed in the 1920s and 30s to have sections used as runways, and Eisenhower may very well been aware of this, or even had seen it happen during the war. Autobahn’s as runways was true even through the Cold War. The A-29 between Ahlhorn and Groβenkneten is one example where NATO planners built a road to accommodate the Air Force if war with the Soviets broke out.

An A-10 Warthog using the A-29 autobahn as a landing strip in 1984

An A-10 Warthog using the A-29 autobahn as a landing strip in 1984

However, this was never the intent of the highway system or of Eisenhower himself. In fact, Eisenhower’s support for the highways had little to do with national defense at all. He understood the need for a system of roads to move the military around the nation and as a means to get civilians out of cities targeted by Soviet nukes, but his primary support was for economic development and traveler safety. The dual purpose of the highway system did interest the Air Force in the 1950s and they even sent people to Europe to investigate, and requested Congress that the highways have for every 50 miles three straight miles to accommodate American bombers. Though the investigators decided it was feasible, the plan was scrapped. What was built, and probably helped begin the myth, were flight strips located next to major highways whose purpose was to serve as auxiliary runways during World War II.

The second myth is that of a requirement to have curves in the road every so many miles. This one is also false, but has more truth in it than the runway story. You can look at any map of the highway system to see that this one isn’t true. There are some abysmally long, straight stretches of road in the Interstate system. One such chunk of asphalt is I-80 outside Salt Lake City to the Nevada border. This section of road crosses the Bonneville Salt Flats and is nearly 50 miles of perfectly straight road.

I-80 as it crosses the Salt Flats between Wendover, NV and Salt Lake City, UT

I-80 as it crosses the Salt Flats between Wendover, NV and Salt Lake City, UT

The Federal-Aid Highway Act (1956) makes no requirements of curves in the highway at any specific distance, but curves are often introduced when the road needs to avoid an area of cultural significance, environmentally sensitive areas, or when the terrain demands a curve. Road designers understand that excessively long “tangent sections” (straight road) can lead to boredom, drowsiness and accidents so curves are included, but the Act itself instructs that roads be as direct as practical and consistent with the land. I couldn’t imagine the Salt Flat section being any one bit longer than it already is, and for that, I’m glad there aren’t any curves.

8. Secret Highways

There are 19 secret highways in the United States. These aren’t clandestine routes used by the Illuminati to get from meeting to meeting, or private roads for the rich and powerful to avoid the rabble in traffic.

I-595 in Maryland... better known as US 50 or US 301

I-595 in Maryland… better known as US 50 or US 301

These are, instead, highways that are officially a part of the Eisenhower Interstate system on paper only. You will not see any signage of their existence on the roadways. The main purpose behind keeping these 19 roads “secret” is to not confuse drivers with additional numbers and signage for the routes. For example: I-305 in Sacramento, CA is signed as Business Loop I-80. The longest of these secret routes is I-595 in Maryland. At almost 20 miles it is known to drivers as US 50 and US 301. Complicating matters is that Florida also has an I-595. Alaska’s four main routes are technically part of the Interstate system, but are signed as Alaska State Routes. This also applies to Puerto Rico. Here is a link to all 19.

9. Looking for Adventure, And Whatever Comes Our Way

Before you fill up the gas tank, crank up Steppenwolf, and cruise down America’s roads, it is advisable to know which ones might end up leading you on a highway to hell. Though America can only claim one road on the world’s most deadly list (Alaska’s Dalton Highway between Fairbanks and Prudhoe Bay) and we certainly have nothing to compare with the North Yungas Road in Bolivia–often cited as the most deadly road in the world, also known as the “Road of Death–we have some dangerous highways of our own.

North Yungas Road in Bolivia. Also called "The Road of Death".

North Yungas Road in Bolivia. Also called “The Road of Death”.

I-15 between Los Angeles and Las Vegas is often credited as the most dangerous road in the United States. According the the Nevada AAA, the 180 mile stretch of road had more fatalities on it than any other in the state. With close to 8 million drivers annually, it isn’t a surprise that I-15 takes the top spot. Apparently, what happens in Vegas doesn’t always stay in Vegas: Drinking and driving and distracted driving account for nearly all the accidents. It doesn’t help that I-15 through San Bernardino County is one of the straightest, most barren strips of concrete in America causing drivers to become inattentive, bored, and forgetful of their speeds.

I-15 in San Bernardino County, CA

I-15 in San Bernardino County, CA

Other highways that rank high in accidents and death include the 8 mile stretch of I-95 near Norwalk, Connecticut. Almost 10% of deaths on the entire 100 mile stretch occur on this little section. I-95 in Florida has nearly 1.73 fatal accidents per mile and has it’s own attorney to help you sue that darn trucker that rear ended you. Between 2000-2010, I-26 in South Carolina saw 325 fatalities with short sections that have triple the amount as other portions closer to Charleston. Finally, I-10 from Phoenix to the California border is notoriously dangerous with 85 fatalities a year.

As you pile the family in the car, remember, you aren’t the only one out there on our secret, hazardous, non-runway interstates.






6 thoughts on “9 Things You May Not Know About the U.S. Interstate Highways

  1. I 238 in California breaks the numbering system in reality it should be called I 2380. It is a spur between two spurs on odd first digit one even first digit. they just do not use four digits. It is the only one in the u.s.

  2. Good article. You mentioned I-580 as non-interstate interstate, which is true. But, these are called spur routes. From my experience they are always non-interstate.

  3. Every time I see how it takes years just for a short section of interstate to be widened, or a new interchange built, etc., I find myself comparing that to the speed with which a good deal of the overall system was built, and am curious what is the record for most miles built in a year, and which year that was. Spent 20 minutes googling for the answer, and couldn’t come up with it. Anyone know?

    • Hi Roy, according to this website–http://www.publicpurpose.com/hwy-intmiles.htm–and I’m not sure how accurate of reliable it is, the answer to your question is 2,463.4 miles in 1964. Hope that helps.

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