The National Highway System: Facts about the world's longest road network

When we talk about highways in the U.S., you gotta ask: Why can't everyone build things like this? It's the dozens of little and big details that make life for drivers logical, convenient, and safe.

The Interstate Highways are their own separate system of roads here. Their official name is the “Dwight D. Eisenhower National System of Interstate and Defense Highways,” named for the president who kicked off the construction of these economic arteries back in 1956. The markings for these roads use signs or numbers that you've definitely seen in photos, American movies, and video games.

A few facts about the overall American road network:
The length of all roads in the U.S. is 4,092,760 miles (6,586,610 km)—number one in the world, about 10% of all the roads on the planet.

• The U.S. is second globally in total Interstate mileage (only China has more).

• All the main Interstates have numbers less than 100 and start with the letter I (for Interstate).

• All East-West routes have even numbers (like I-90).

• North-South routes are designated with odd numbers (like I-5).

• Numbers divisible by five are considered the main arteries among the primary routes (like I-10).

Interstate highway standards: You get at least two lanes in each direction; lane width is about 12 feet (3.7 meters); and there's always a median separating the direction of travel.