Most Route 66 attractions are all about what’s on the road, but in Chelsea, Oklahoma, one stop takes you underneath the pavement and deep into local history. The Route 66 Pedestrian Underpass in Chelsea, Oklahoma offers something rare on the Mother Road: a chance to walk under the highway itself. Built during the heyday of Route 66, when traffic was heavy and constant, the underpass provided a safe way for pedestrians to cross from one side of town to the other without having to dodge passing ca