Connecticut based US Flagged line, American Cruise Line, just announced they will be building 4 new river boat ships. Construction just began on the first two ships with the first entry into service expected to be Spring 2015. Each ship will carry between 150-200 pax. They will sail routes on the Mississippi or Columbia River.
The last one is expected to be inaugurated in 2017.
They didn’t announce the shipyard yet but my guess is it will be Chesapeake Shipbuilding in Salisbury, MD.