(WHTM) — Interstate highways tend to be long, major highways that carry thousands of cars on a daily basis.

The combined length of all the interstates in Pennsylvania make up 1,757 miles of highway. The system carries 24% of all vehicle travel in the state, according to tripnet.org. Some interstates can be in excess of 300 miles long in the state.

But what are the shortest interstates in the Keystone state?

Interstates can be categorized as primary interstates and spurs. Primary interstates are normally one to two digits while the spur interstates are three digits.

The shortest primary interstate in the state is Interstate 86. The interstate only travels 7.30 miles in Pennsylvania, but the entire length runs through northern Pennsylvania and through the Southern Tier of New York.

The shortest spur interstate is Interstate 579. This interstate is a spur off of Interstate 79, which runs north to south through Pennsylvania.

It is the shortest signed interstate in Pennsylvania and is only 1.77 miles long. It is located in Pittsburgh and is also called the Crosstown Boulevard. The spur was constructed in the early 1960s.

At one time, the Interstate 579 was the shortest in the country.