America, Downhill
Have you ever wondered how long you could coast (on a bike or car) downhill and still reach the ocean? Virtually every road goes uphill and downhill, but is there a way to start up on a mountain somewhere, and never go downhill? I'm sure there's a way to figure this out with elevation maps, road maps, and a ton of computing power. My question would be, specifically: what's the longest distance on roads you could travel, using only gravity to propel you? That's it. If you want more, Randall Munroe of XKCD partially answered this question in a What If? post: https://what-if.xkcd.com/154/ Peace, Chris