Interstate Highways are a collection of controlled-access highways in the United States. The original Interstate network was completed in 1986 — 35 years after authorization by Congress. Since the completion of the original network, the Interstate System has added an extra 48,000 miles
US Numbered Highways (also called US Highways) are a network of roads and highways connecting the contiguous United States. As of August 2022, the U.S. numbered highway system consists of 157,724 miles of urban and rural roadways.
State Highways are generally primary and secondary roads, sometimes built to Interstate standards, linking cities within a State. Each state is responsible for route numbering and layout meaning routes vary state to state.