American Cruise Line is a small ship cruise line that sails on calm inland waterways. There used to be cruises from Philadelphia through the Chesapeake and Delaware Canal, down the Chesapeake Bay, then up the Potomac River to Washington. Along the way they visited charming and historic small towns on the bay.
American Cruise Line's ships hold less than 120 passengers and have the advantage of being small enough to visit interesting ports that big cruise ships cannot reach. The ships are modern and built in America (Salisbury, Maryland). Many staterooms have private balconies. Read an American Cruise Lines cruise review.
American Cruise Line has no cruises from Philadelphia scheduled. There are American cruises from Baltimore, which isn't far.