"Computing the optimal road trip across the U.S."

"[W]e needed to look up 2,500 directions to get the 'true' distance between all 50 landmarks... Now with the 2,500 landmark-landmark distances, our next step was to approach the task as a traveling salesman problem: We needed to order the list of landmarks such that the total distance traveled between them is as small as possible if we visited them in order. This means finding the route that backtracks as little as possible...."