(WHTM) — Pennsylvania is full of many roads, and we know that there are 23 interstate highways that pass through the state. But how many of those thousands of roads are considered US Routes?

At least 24 different roads have been designated US Routes in Pennsylvania. This does not include auxiliary routes, such as business routes. The longest US Route that goes through the state is US Route 6, which spans from the Ohio state line all the way to the New York state line in Pike County. This road is 403 miles in length.

The shortest US route through Pennsylvania is less than one mile long. US Route 206 is a north-south route that mostly runs through New Jersey. The nearly half-mile length is when a toll bridge carries it over the Delaware River in Pike County and heads back into New Jersey. The road in pennsylvania stretches only 0.46 miles.

The main differences between a US Route and a US Interstate are signs, exits, and lanes. According to Route 66 Tours, Interstates tend to have higher speeds, which can provide greater traffic flow. Another difference between the two has to deal with exits.

Route 66 Tours says that US Routes typically go through many towns during their length. It all allows for stop lights to be on portions of the route as well as turns onto local streets. Interstates only have numbered exits that use on and off-ramps instead of actual roads.

Signage is also different, with US Routes and Interstate Highways featuring different signs, often called ‘shields’, and coloring. You can tell you are on a US Route with a black and white sign that looks like a shield, with an Interstate shield being a different shape and featuring red white, and blue coloring.

You can compare the two signs down below.

Photos from Getty Images

As with Interstates, US Routes tend to be even numbers running from east to west and odd numbers running north to south. The numbers also increase from east to west. For example, US 1 follows the Atlantic coast, with US 101 running the Pacific Coast.

More information on highways and other major roadways can be found here.