Randall (xkcd) wrote,

The Longest Drive in the US

So a friend and another friend and I were thinking of taking a weekend road trip up to New England in a couple weeks, and if we end up in Newmarket, NH on the first night, it will be the longest drive I've ever done.

And that got me wondering -- what's the longest drive possible in the continental 48 US states, taking the shortest path between two points?

Using Google Maps, I first tried going northeast to southwest, northern Maine to western California, with a max time of about 2 days 16 hours, but I found it was further if I went from Washington to Key West. I picked a road out on the edge of a point in Washingon State and a road down at the end of the Truman Annex in Key West, and got 2 hours 23 minutes. ALMOST three days! These were the points (paste into maps.google.com to see the path:)

48.374554,-124.722719 to 24.546323,-81.810776

I was trying to figure out if I could push it over three days somehow, since I was less than an hour away. I noticed that the final road (a loop) in the Truman Annex was one-way, so I shifted the endpoint down to the end of the road, just to squeeze out those extra few moments. Bizarrely, the total driving time DROPPED three hours.

48.374554,-124.722719 to 24.54605,-81.809714

It's still the same path into the Truman Annex -- it's just that somehow the lat/long shifting by a few feet changes the overall path taken. Specifically, making that lat/long change makes the course route through New Orleans, then along the coast. People have found similar quirky long paths that take you out over the ocean before, but this one raises two questions:

(1) What does this quirk say about Google's algorithms? They're clearly not running full best-path finders on the road network, and there's probably some crazy geometric shortcutting going on. I'd love to learn more about Google/Mapquest direction-finding algorithms -- it's one of the problems that got me interested in those sorts of algorithms in the first place.
(2) Are there two points in the contiguous 48 states that are three days apart, according to Google? Can anyone beat my 2 days 23 hours?

(Note: to easily get the lat/long of a point to experiment with routes, just click "link to this page", and the lat/long of the point you're looking at are after the ll= in the URL)

edit: gfish found a 3 day 2 hour route by going from the CA/OR border over to Maine with some particularly bad routing around the destination.

I wonder what the longest honest route is, but I also wonder what the longest route Google will give is.
  • Post a new comment

    Error

    default userpic

    Your IP address will be recorded 

  • 28 comments