The Interstate Highway System, which connects different states, is spread across the US territory by a grid. These highways represent the second largest nationwide network of roads in the world. The roads have wide slopes, convenient extended renumbered entrances / exits to other highways or city streets, made only in the right "pockets" along the way. Crossings with other roads are performed only at different levels.

Interstate Highway system is an integral and high-quality part of the US National Highway System, which also includes US routs (public roads or US highways), and State roads (inside -trade roads.)