What does the “U.S.” in U.S. Highways stand for?

When was the United States Numbered Highway System first established?

Which highway is famously known as the “Main Street of America”?

What nickname was given to U.S. Route 66?

What nickname was given to U.S. Route 66?

Which is the longest U.S. Highway?

U.S. Route 1 runs between which two states?

Even-numbered U.S. Highways generally run in which direction?

U.S. Highway signs are usually in what shape?

U.S. 20 runs from coast to coast. Which two states does it connect?