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Why Does Hawaii Have Interstate Highways?
by the mag - August 14, 2008 - 7:31 PM

hawaii-h1.jpgWhile we’d like to believe Hawaii’s Interstate system was created for the sole purpose of annoying the late George Carlin, the name is actually a misnomer. Not all Interstates physically go from one state to another; the name merely implies that the roads receive federal funding. The three Hawaii Interstates (H1, H2, and H3) became Interstates as part of The Dwight D. Eisenhower System of Interstate and National Defense Highways to protect the U.S. from a Soviet invasion by making it easier to get supplies from one military base to another.

This explanation originally appeared in the “25 Most Important Questions in the History of the Universe” issue of mental_floss magazine.

Comments (11)
  1. H3 is also probably the most expensive interstate highway per mile, and it took almost 40 years from initial planning to completion.

  2. Thanks for the info. I lived in Hawai’i for 6 months and couldn’t figure that out. :-D

  3. Wisconsin has an Interstate that is really an intrastate… I-43 has termini at Beloit and Green Bay.

    Wow, actually, there are lots…

    4, 12, 16, 17, 19, 27, 37, 43, 45, 49, 73, 86 (western portion), 87, 88 (both portions), 96, 97, 99

  4. To follow up on PointSpecial,
    I-12 in Louisiana begins in Baton Rouge and ends just past Slidell on the north shore of Lake Pontchartrain, when it once again meets I-10, which dips south to hit New Orleans, heads back north before going into Mississippi…

  5. And more fun interstate facts:

    Interstates are numbered from south to north and west to east. East-west interstates end in even numbers, while north-south interstates end in odd numbers. Spurs and loops always have 3 digits.

    Meanwhile, mile markers start from 0 in the west and increase as you move east on east-west interstates and from 0 in the south and increase as you move north on north-south interstates.

  6. Just to add to Lindsey’s info, spur and loop designations are derived from the interstate number they’re on with an additional first digit; even first digits signify loops, odd first digits signify spurs (e.g. I-610 is a loop on Interstate 10, I-310 is a spur).

  7. Another interesting fact (unless things have changed), I-97 from Annapolis to Baltimore, MD is the shortest (2 digit) interstate highway at only 18 miles long.
    I-90 from Seattle to Boston is the longest at nearly 3100 miles.

  8. Interstate 10 just east of Orange, Texas has the highest Interstate Highway mile marker in the country, mile marker 880. The mile markers reset at every state line, and Orange to El Paso is a good hike.

  9. PointSpecial left out one: Intrastate 66 in northern Virginia — it peels off of 81 just south of Winchester, Virginia and ends at the Potomac River just before crossing into DC.

  10. I-291 in Connecticut is the exception that proves two rules:

    1) Two consecutive spurs or loops off the same interstate are not numbered identically: The CT I-291 is less than fifty miles from the next spur, I-291 in Springfield, MA, the closest identically numbered interstates in the country.

    2) Odd numbered designations indicate a North-South intersatate: Orignally intended as a loop around Hartford, the project was mired in litigation so long that the only piece that was ever eventually built connects I-91 on the west end and I-84 on the east end.

  11. Great info! I always wondered why there were so many I-*80’s in the Bay Area.

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