U.S. Bancorp is buying the U.S. municipal bond trustee business of Deutsche Bank as the bank bulks up its corporate trust services.

The Minneapolis-based bank said Monday that it has entered into a definitive agreement to purchase the business, which will add about $57 billion to the more than $3 trillion in assets U.S. Bank currently has under administration in its corporate trust division.

As a bond trustee, U.S. Bank handles payments and serves as an independent link between the municipality that issued a bond and the investors who bought the debt.

The deal adds an additional 1,100 contracts to the 125,000 trust and agency contracts U.S. Bank has, many of them in California, Mississippi, New York, Tennessee and Texas.

A price for the bolt-on acquisition, expected to close in the third quarter, wasn’t disclosed.

In a statement, Deutsche Bank said it was selling the business to sharpen the focus of its existing global trust operation on other areas such as asset-backed securities.

Bryan Calder, president of U.S. Bank Global Corporate Trust Services, said the purchase strengthens the bank’s position as the country’s top provider of municipal trustee and agency services, where it has 30 percent market share. It also fills in some geographic gaps, he said, such as Mississippi.

U.S. Bank has been growing its corporate trustee services for years as the industry consolidates. It likes the fee-based business for its steady, predictable revenue stream.

Municipal bond trustee services now generates about 60 percent of its corporate trust revenue, Calder said, with 40 percent driven by securitization. Towns, states and local governments are “going to have to continue to finance their projects,” he said.

The bank has bought a number of corporate trust departments over the years. In 2010 it bought Bank of America Corp.’s securitization trust administration business. In 2005 it bought the corporate trust and institutional custody businesses of Wachovia Corp.

“There’s a steady stream of new deal opportunities,” Calder said.