The Ultimate American Road Trip Guide

The Complex History of the U.S. Interstate Highway System

This Simple Map of the Interstate Highway System Is Blowing People’s Minds

U.S. Interstate Highways, as a Transit Map

Navigate the US Interstate System Like a Pro Ever wondered how America’s Interstates are numbered? Here’s the scoop: Main east-west routes are even numbers ending in 0 (like I-10 to I-90), running horizontally. North-south are odd numbers ending in 5 (I-5 to I-95), going vertically. Lower numbers mean farther south/west; higher ones are east/north. For spurs: Three-digit highways (e.g., I-295) match the last two digits of their parent route. Even first digit? It loops back. Odd? It’s a one-way b