http://www.amtrak.com/3-day-sale-northeast-regional-train Presumably could be combined with separate tickets to PHL/WAS/etc. or with the 2-for-1 offer on the Downeaster service to NH and Maine. Rules say the fares are not valid to/from intermediate cities, but I've never known Amtrak to care about hidden city ticketing. Travel to/from: New York City and Boston - $37 New York City and Providence - $32 New York City and New Haven- $20 Exclusively available at www.Amtrak.com. Valid for sale July 21 - 23, 2015. Valid for travel August 25 - September 17, 2015. Blackout dates: September 4 and 7, 2015. Valid for travel on the Northeast Regional train service between the following select city pairs only: - New York, NY - New Haven, CT - New York, NY - Providence, RI - New York, NY - Boston, MA (South Station/Back Bay) and Route 128, Westwood, MA Offer does not include travel to/from any intermediate cities. Once purchased, tickets are non-refundable; exchanges are permitted prior to the original travel date. Valid for Coach seats only; no Business class upgrades permitted. Seating is limited; seats may not be available on all trains at all times. Fares are subject to availability. Discounted one-way fares valid for all adult passengers; no additional discounts apply. Not combinable with any other discount offer. In addition to the discount restrictions, offer also subject to any restrictions, blackouts and refund rules that apply to the type of fare purchased. Fares, routes and schedules are subject to change without notice. Once travel has begun, no changes to the itinerary are permitted. Other restrictions may apply.