If you've ever driven west on Interstate 80 through Nebraska, you've seen one of the flattest and emptiest roads in America ... and you probably had some time to ponder life's most important questions. For example, why is the highway called "I-80," anyway? And why do some interstate names have one, two or three digits?
Why is one road named I-5 while another is I-480? We take a closer look at the digits on those red, white and blue shield-shaped signs.