Spurs, Bypasses and Beltways: Auxiliary Interstates in Hawaii, Idaho, Utah, Vermont and West Virginia

The end of Utah State Route 186 at a junction of Interstate 80 and Interstate 215, with the Wasatch Mountains in the background. (Photo credit: Wikipedia)

Interstates with three digit numbers are known as auxiliary interstates. These highways can be classified as one of three types. Spurs connect to the main interstate at one end. Bypasses are highways that connect at both ends to the interstate. The last type is the beltway which forms a circle around a large city. This highway intersects the interstate at two points of the circle.

Some states such as Alaska, Arizona and North Dakota do not have any auxiliary interstates. Six states have only one each. In the state of Hawaii  H201 is a road of just over four miles which provides an additional route from Halawa Heights to Honolulu. Interstate 84 in Idaho has an auxiliary route of 3.62 miles in Boise. Interstate 184 takes travelers to the northern section of Boise and Garden City. Utah has one auxiliary for Interstate 15. For a circle of 29 miles, Interstate 215 provides a route to the suburbs of Salt Lake City. In Wyoming the one mile of Interstate 180 connects I-80 with Business I-80 in Cheyenne.

Interstate 189 is a very short route connected to Interstate 89 in Vermont. This highway  of 1.49 miles joins I-89 to Route 7 outside South Burlington. In West Virginia Interstate 470 travels for 6.69 miles. This road departs from Interstate 70 at Exit 5A and travels east across the Ohio River into the state of Ohio.

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