Ever wondered how the highway and interstate numbers came to be? What do they even mean if they mean anything at all? Behind those numbered shields displayed on the signs is a mathematical logic grid ...

The story of America’s interstates is usually told as a straightforward tale of postwar progress, but the real origins are stranger and more contested than the green signs suggest. The Dwight D.

It’s been called the 51st state, a perpetual motion machine, a journey with no end. It is the world’s largest public-works project. In a nation divided by geography and politics, the United States ...