Mount Greylock – Mount Williams loop from Harriman-and-West Airport

If you're looking for a serious challenge with immense rewards, the Mount Greylock – Mount Williams loop from Harriman-and-West Airport is a difficult jogging route that delivers. This demanding 12.9-mile (20.7 km) journey packs in 4166 feet (1270 metres) of elevation gain, typically taking around 3 hours and 24 minutes to complete. It's a perfect pick for experienced trail runners seeking a strenuous outing with panoramic views across the Berkshires.

What to expect on Mount Greylock – Mount Williams loop from Harriman-and-West Airport

This loop is a true test of endurance, guiding you through dense red spruce forests and over rugged, steep terrain. You'll encounter aggressive ascents, particularly on sections leading to Mount Greylock's summit. The payoff is incredible: from Mount Williams, you can gaze upon Williamstown, North Adams, and the distant Taconic Range. The ultimate reward is reaching the summit of Mount Greylock, Massachusetts' highest point, where the Veterans War Memorial stands, offering expansive views stretching into New York, Connecticut, Vermont, and New Hampshire. Expect a mix of challenging trail running and rewarding vistas, making it ideal for those who thrive on significant elevation changes.

Planning your visit

Given the strenuous nature of this Mount Greylock Mount Williams loop, sturdy trail shoes are highly recommended. Be prepared for varying weather conditions, as mountain weather can change quickly, and carry sufficient water, as sources may be limited along the route. Parking for this challenging trail can typically be found at trailheads on Hopper Road or Notch Road in Williamstown or North Adams, which are close to Harriman-and-West Airport.

Trail details

• Distance: 12.9 miles (20.7 km)
• Elevation gain: 4166 feet (1270 metres)
• Difficulty: difficult
• Estimated time: 3 hours and 24 minutes