How do highway exit numbers work?


Quick Answer

Highway exit numbers typically start from one as the highway enters a new state. The exit number increases by one unit per mile until the highway crosses the state line.

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How do highway exit numbers work?
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Full Answer

Two exit numbering methods in the United States are sequential numbering and distance-based numbering. The sequential numbering method numbers the exits sequentially. When adding a new exit between two existing exits, the new exit has a suffix in addition to a number, such as Exit 21A on the New York State Thruway. Some new exits in Florida have the suffix C.

The more common exit numbering method is distance-based numbering. Most exit numbers start at one and the number increases by miles traveled. Some highways, such as the Interstate 70 in Wheeling, WV, start with exit 0.

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