The Washington and Old Dominion Trail (W&OD) runs 45 miles between Shirlington, VA and Purcellville, VA. The trail is paved and is in excellent condition. The W&OD is popular with walkers, cyclists, and joggers, so runners should exercise the appropriate trail etiquette: keep to the right, run in single file, and keep headphone noise to a minimum (or avoid headphones altogether). Despite the trail’s popularity, it includes many open stretches that will allow runners to add pace pickups into their workouts. Still, the trail consistently runs through urban and suburban neighborhoods, and there are some at-grade street intersections along the way. Always be cautious. Finally, the W&OD offers many gradual rolling hill segments, affording runners the opportunity for varied terrain in their workouts.