June 18 - September 4
Lowell National Historical Park will have trolley shuttles, Thursday-Monday, between the Visitor Center (246 Market St.), Boott Cotton Mills Museum (115 John St.) and Suffolk Mill (600 Suffolk St.). (No trolley service on Tuesday and Wednesday)
Schedules vary, so please check the trolley schedule at the Visitor Center, the Boott Cotton Mills Museum, and at trolley stops. Trolley rides are free.