Marine Midland Bank was an American bank formerly headquartered in Buffalo, New York, with several hundred branches throughout the state of New York. In 1998, branches extended to Pennsylvania. It was acquired by HSBC in 1980, and changed its name to HSBC Bank USA in 1999. As a result of several transactions since the turn of the millennium, much of what was once Marine Midland is now part of KeyBank with the exception of Downstate New York and Pennsylvania. that is now part of Citizens Bank. Branches in Seattle are part of Cathay Bank .