JPMorgan Chase (JPM) CEO Jamie Dimon is bullish on the future of retail bank branches as the largest U.S. bank continues its expansion.

"There are people in business who always look at facts. OK, we have a million people a day visit branches. So millennials are doing it less, they're still doing it,” Dimon told Yahoo Finance's Andy Serwer in an exclusive interview at the unveiling of JPMorgan’s new flagship bank branch in Midtown Manhattan.

Approximately 21 million different customers will visit a JPMorgan branch each year, he added. While JPMorgan boasts more than 50 million digital users, the physical branches are crucial to supporting local small businesses and middle-market companies as well as consumers.

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However, over time, the format of a bank branch will change, Dimon acknowledged. The newer format features more ATMs, fewer tellers, and more advisors. Those advisors may give advice to small businesses, private clients, or cutomers looking for a mortgage.

“The advice part is going up. The operational part is going down. On average, the branch will get smaller, ” he said.

The future of the branch has become a topic of discussion among the most prominent banking players in the U.S.

Citigroup (C) CEO Mike Corbat said at a Fortune event last week that the firm’s strategy is shifting toward a “physical light” and forcing “a lot more digital interaction” with customers.

"I'm not prepared to lock all the branch doors yet," he said, adding, "I think you'll see the nature of physical presence in branches probably change materially."

Elsewhere, Goldman Sachs (GS) wants to disrupt banking with its young online consumer arm Marcus by Goldman Sachs.

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"There is no reason why you need to walk to a branch to do banking,” Goldman’s Harit Talwar, the head of global consumer, told Yahoo Finance at the same event.

Meanwhile, JPMorgan is on the expansion trail, with plans to open 400 new branches in the next few years across 20 new markets, including some that are “right at the heart” of some of the bank’s competitors.

In the last year, JPMorgan entered new markets in Washington, D.C., Philadelphia, and Boston. This year, new branches will be opened in Charlotte, Minneapolis, St. Louis, and Nashville.

By 2022, JPMorgan Chase expects to have a branch within 93% of the U.S. population.

The expansion will also create “thousands of jobs,” Dimon said. JPMorgan employs 49,100 people across its network of more than 5,000 branches.