The Longest (and Shortest) Interstate Highways Across the United States

The Interstate Highway System was created in 1956 to aid travel across the United States, assist with the transportation of goods throughout the country, and be used for emergency situations or quick troop deployment. The interstates were built to be major roadways that run through multiple states, with some even reaching from one coast to the other. But what is the longest interstate in the U.S.? The team at Alan’s Factory Outlet compared the many miles our country’s 77 interstate routes cover to see which is the longest. The highways that make up the U.S. interstate system span a wide variety of distances, with the longest reaching 3,020 miles and the shortest just 8 miles long.

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Longest and Shortest Interstate Highways

Which Interstate Highway Is the Longest?

The longest interstate in the U.S. is Interstate 90, with a length of 3,020 miles that runs from east to west between Boston, Massachusetts, and Seattle, Washington. Interstate 90 goes through 13 different states as it crosses the country, the second most of the longest highways in the U.S. interstate system.

The interstate that services the most states is Interstate 95, which runs north-south between Miami, Florida, and Houlton, Maine. Interstate 95 is 1,908 miles long, putting it at sixth on the list of the longest interstates in the U.S.

The 10 Longest Interstate Highways in the U.S.

  1. I-90: 3,020 miles
  2. I-80: 2,900 miles
  3. I-40: 2,557 miles
  4. I-10: 2,460 miles
  5. I-70: 2,151 miles
  6. I-95: 1,908 miles
  7. I-75: 1,786 miles
  8. I-94: 1,585 miles
  9. I-35: 1,568 miles
  10. I-20: 1,539 miles

Which Interstate Highway Is the Shortest?

The shortest interstate highway in the U.S. is Interstate H-2 with a length of just 8 miles, as it runs between two Hawaiian cities, Pearl City and Wahiawa. The shortest interstate in the contiguous U.S. is the second Interstate 87, which is 13 miles long and runs between Raleigh, NC, and Wendell, NC. Interstate H-2 and North Carolina’s I-87 are two of 27 interstate highways that were built to serve only one state.

The 10 Shortest Interstate Highways in the U.S

  1. H-2: 8 miles
  2. I-87 (NC): 13 miles
  3. H-3: 15 miles
  4. I-97: 18 miles
  5. I-11: 23 miles
  6. I-14: 25 miles
  7. H-1: 27 miles
  8. I-2: 47 miles
  9. I-86 (ID): 63 miles
  10. I-19: 63 miles

What Do Interstate Highway Numbers Mean?

Did you know that the numbers assigned to each interstate can tell you which direction it goes in or if it’s one of the major routes? The primary Interstate Highways, which are the ones covered here, are assigned one- or two-digit route numbers, while auxiliary interstate highways have three-digit numbers. Odd-numbered interstates run south to north, and even-numbered interstates run west to east. You’ll find that lower numbers are used for routes that run through the south and west, while higher-numbered routes are located in the north and east. If an interstate’s route number is divisible by “5,” it represents a major coast-to-coast or border-to-border route.

You may have noticed that within the list of interstate highways, some of the interstates begin with an A or H: These represent the interstates that run through Alaska and Hawaii. The Federal Highway Administration funds these routes under the same program as the rest of the Interstate Highway System, although Alaska does not have to meet the same federal interstate standards as the other 49 states.

It’s also worth noting that five of the route numbers in the Interstate Highway System have been duplicated but are located in different states or regions of the U.S. to avoid confusion. Below is a list of the five duplicated route numbers to keep an eye out for when looking at the U.S. interstate map:

  • I-76
    • I-84
    • I-86
    • I-87
    • I-88

Do yourself a favor and make a mental note of how the Interstate Highway System has been numbered, just in case you ever find yourself lost traveling from your garage to your destination while on a road trip.

This informational infographic is brought to you by Alan’s Steel Buildings.

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By Alan Bernau Jr