But first you need to know a little about the interstate highway system.

But during that period the interstate system grew only to 46,300 miles, or 7.9 percent.

Construction of the interstate highway system started in the late 1950s.

I-74 was part of the original plans for building Iowa's interstate system.

Thanks to the interstate highway system, the nuclear threat helped to do much the same thing.

When Eisenhower became president, he worked to create the interstate highway system.

The $230 million, 4.1-mile bridge is seen as a key link in interstate highway system.

His major project was building the interstate highway system using federal gasoline taxes.

"Right now, it's treated as an access point to the interstate highway system."

For work on the interstate system, states put up 10 percent and Washington 90 percent.