Interstate Highway System facts for kids
  
Highway shields for Interstate 80, Business Loop Interstate 80, and the Eisenhower Interstate System
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Interstate Highways in the 48 contiguous states. Alaska, Hawaii, and Puerto Rico also have Interstate Highways.
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Quick facts for kids System information |
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| Formed: | June 29, 1956 |
| Length: | 48,756 mi (78,465 km) |
| Highway names | |
| Interstates: | Interstate X (I-X) |
The Interstate Highway System is a system of freeways in the United States. It was first designed by Dwight D. Eisenhower in the 1950s. The Federal Aid Highway Act of 1956 was used to pay for construction. It was mostly built from the 1950s through the 1980s. But more freeways were built later. It is now about 49,000 miles long. Some interstates have tolls, but most do not. Most interstates have rest areas every few dozen miles.
What is needed
To be an Interstate Highway, there cannot be any stoplights. To get on or off the freeway, an interchange is needed. The speed limit is usually at least 55 miles per hour. It must have at least two lanes going each way. The lanes must be at least 12 feet wide. There has to be a median or barrier between cars going different directions.
Numbering
North-south interstates have odd numbers. The numbers go up from west to east. East-west interstates have even numbers. The numbers go up from south to north. One and two digit freeways go long distances. Three digit freeways go into or around cities. Freeways that go into cites are called spur routes and start with an odd number. Freeways that go around cities are called loop routes and start with an even number. The last two digits in a spur or a loop route are the same as the freeway it started from.
See also
In Spanish: Sistema Interestatal de Autopistas para niños
