Runners start and finish the out-and-back course for the Gar Williams Half at the Carderock Recreation Area, which lies just to the west of where I-495 and the Clara Barton Parkway meet. From there, runners follow the C&O Canal Pathway as it winds in tandem with both the canal and the Potomac River that separates Virginia and the District of Columbia, all the way down to the half-way turnaround point just past North Glebe Road.
(MORE: Gar Williams Half Marathon event details)