Cambridge Half Marathon and 5K - Massachusetts

Cambridge Half Marathon and 5K - Massachusetts runs over October 31 and November 1, 2026, based at the CambridgeSide mall in Cambridge, Massachusetts. The 5K goes first, at 10 a.m. on Saturday, with an out-and-back along the Charles River and views of the Boston skyline. The USATF-certified half marathon (13.1 miles) starts at 7 a.m. on Sunday and runs on Memorial Drive past landmarks including the John W. Weeks Footbridge, MIT and Harvard Stadium.

Two days of racing lets you double up: run the 5K as a shakeout on Saturday, then race the half on Sunday, or simply pick the one that matches your training. River-side road running is flat and rhythmic, which makes the certified half a fair place to chase a personal best or a qualifying time. Proceeds go to local organizations including Cambridge Camping and the City of Cambridge Scholarship Fund.