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U.S. National Network Routing

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U.S. federal law dictates that truck/trailer combinations with width greater than or equal to 102 inches, trailer length greater than or equal to 53 feet, or both, must stay on designated State and National Network roads to the maximum extent possible. The National Network includes the Interstate Highway System (several minor segments are not included), and many selected U.S. and state numbered highways.

Many states, however, provide specific exemptions to this national rule. Recent improvements to the routing algorithm now account for these exemptions. As a result, the algorithm generates more practical routes with increased freedom to travel off the network in areas where exemptions exist.

Highlights of state exemptions include:

  • The following states allow all non-OSOW (over-sized, overweight) truck/trailer combinations freedom of travel off of the State + National Network:
    • Alaska, Arkansas, Colorado, Georgia, Indiana, Iowa, Kansas, Mississippi, Montana, Nebraska, Nevada, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Texas, Utah, Washington, and Wyoming.
  • The following states allow all non-OSOW truck/trailer combinations EXCEPT twin trailers freedom of travel off of the State + National Network:
    • Hawaii, Maine, Minnesota, and Virginia.
  • The following states restrict all non-OSOW truck/trailer combinations to the State + National Network with a width of 102 inches or greater:
    • Alabama, Florida, and New Jersey.
  • The following states restrict all non-OSOW truck/trailer combinations EXCEPT 28-foot trailers freedom of travel off of the State + National Network: Illinois, Maryland*, Missouri, Oregon, and Pennsylvania**.
    • *MD also allows 48-foot trailers with a width of 102 inches.
    • **PA also allows trailers with a 53-foot length if they are only 96 inches in width.
  • The following states restrict all non-OSOW truck/trailer combinations to the State + National Network with 53-foot length or greater:
    • California, Connecticut, Delaware, Idaho, Louisiana, Massachusetts, New Hampshire, New Mexico, North Carolina, Rhode Island, Vermont, and Wisconsin.
  • The following states restrict all 102-inches wide or 53-foot long non-OSOW truck/trailer combinations to the State + National Network:
    • Arizona, Washington DC, Kentucky, Michigan, New York, and Tennessee.
  • West Virginia is the only state with NO truck/trailer combination exemptions to the State + National Network, including 48-foot and 96-inch combinations.
Last updated November 28, 2022.
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