UPDATE 1-U.S. Bancorp to buy AmeriServ's corp bond business

* Deal to give U.S. Bank $2.1 trln assets under management

* No price tag, closing date given

NEW YORK, April 8 (Reuters) - U.S. Bancorp (USB.N) unit U.S. Bank will buy the corporate trust bond administration business of AmeriServ Financial (ASRV.O), the financial firms said on Wednesday.

The deal gives U.S. Bank $2.1 trillion in assets under management and nearly 670,000 bondholders, U.S. Bancorp said, adding it struck the deal to boost U.S. Bank's foothold in Pennsylvania and to take advantage of "difficult economic times."

No price tag or expected closing date was given for the transaction.

The "growing costs of administration" had become a problem for AmeriServ, owner of regional trust AmeriServ Trust and Financial Services Company, the companies said.

U.S. Bank runs 2,791 banking offices and 5,164 ATMs in 24 U.S. states. (Reporting by Jonathan Spicer; Editing by Tim Dobbyn)