The days when any old person could stick up a thumb and hitch a ride across America are long gone — but starting today, one brave robot is bucking the trend by hitting the road with nothing but a pair of boots, a digital smile, and an implicit faith in the kindness of strangers. HitchBOT — a durable humanoid robot designed to be passed, person-to-person, on journeys across the world — has arrived in the United States, after enjoying previous trips through Canada and Europe. The guiding principle behind HitchBOT is simple: If you see it, pick it up and take it along, serving as a faithful companion until you pass it to someone else.