PENNSYLVANIA (WHTM) — At some point, we have all driven on a Interstate. Whether it’s Interstate 81, Interstate 83, or even the Pennsylvania Turnpike.

But, has anyone wondered about just how many interstates pass through the Keystone State, or even, why interstates exist?

According to the U.S Department of Transportation, they would be the safest road network in the United States and one of the safest, if not the safest, in the world. Its design concepts would be used on non-Interstate roads to make them safer as well.

The Interstate Highway System came into effect when President Dwight D. Eisenhower signed the Federal Aid Highway act of 1956. The first ever interstate was Interstate 70 in Kansas, according to the United States Department of Transportation.

Each state is responsible for its portion of the highway that runs through its state. In total, Pennsylvania has a total of 23 interstate highways throughout the state. This includes 12 primary routes and 11 auxiliary routes.

Primary Interstates Include the following:

  • Interstate 70
  • Interstate 76 (Also known as the main line of the Pennsylvania Turnpike. It is also the longest Interstate in the state at 349.67 miles)
  • Interstate 79
  • Interstate 80
  • Interstate 81
  • Interstate 83
  • Interstate 84
  • Interstate 86
  • Interstate 90
  • Interstate 95 (The shortest interstate in the state at 44.25 miles)
  • Interstate 99

Auxiliary Interstates are mostly spur highways, according to The term ‘spur’ or ‘spur route’ refers to a short roadway that forms a branch from a longer and more important road such as a major roadway or Interstate Highway. They normally come into play around larger metro areas.

They include:

  • Interstate 176
  • Interstate 180
  • Interstate 276
  • Interstate 279
  • Interstate 283
  • Interstate 376
  • Interstate 380
  • Interstate 476 (The longest spur highway in the state. 132.10 miles long)
  • Interstate 579 (The shortest spur highway in the state 1.57 miles long)
  • Interstate 676

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

Interstates are a vital part of travel in the United States. It is hard to think of a time when Interstates were not apart of daily life in the country.