While the parade of failures still represents a mere fraction of America’s small banks, it underscores a growing divide between them and large institutions like Goldman Sachs, JPMorgan Chase and U.S. Bancorp, which are slowly growing stronger as the economy improves.

Burdened by worsening commercial real estate loans, many small banks’ troubles are just beginning. Many analysts say that the now-toxic loans could sink hundreds of small lenders over the next few years and place a significant drag on the economy.

Already, the bank failures are placing enormous strain on the F.D.I.C. and its fund, which keeps depositors whole. Flush with more than $50 billion only two years ago, the fund recently fell into the red.

The prospect of more failures has led the F.D.I.C. to seek new ways to replenish the fund with higher and earlier payments by healthy banks, even after setting aside reserves for future losses.

The initial wave of failures has also unsettled some communities, even though most of the troubled institutions have been bought by other banks rather than shuttered. While deposits are safe thanks to federal insurance, the new buyers often do not have the same ties to local businesses as the former owners.

In some cases, they tighten lending and make it harder for longtime customers to obtain loans or favorable terms. In other cases, managers of the new bank make other changes, like ending offers for high-interest certificates of deposit and calling in certain lines of credit. In the longer term, some new owners are likely to close branches of the bank they have acquired in order to cut costs.

“In the near term, bank failures can be painful,” said Sheila C. Bair, the chairwoman of the Federal Deposit Insurance Corporation. But a bank that is teetering on collapse is not going to lend, she said, and “that’s not good for the economy.”

Regulators expect closures to ripple through hundreds of small banks over the next couple of years, especially in the Midwest and Southeast, where lenders have been hard hit by the recession.

These banks loaded their balance sheets with loans to home builders and other property developers to make up for lost business in credit card and mortgage lending that bigger competitors wrested away. They eased their lending standards during the boom years and made big bets on new housing developments, strip malls and office projects. Now, many of those deals are falling apart, and the lenders are scrambling to raise capital to cushion the losses.

“These banks were big enough that they could do loans that were fairly sizable,” said John R. Chrin, a former investment banker who is now an executive in residence at Lehigh University. “If they go bad, they are toast.”

The pace of bank failures is expected to accelerate in the coming months. There were just 25 bank failures in 2008 and just 10 in the five previous years. But in September alone, regulators took over 11 banks in nine states that were saddled with soured commercial real estate loans, from Corus Bank, a $7 billion construction lender based in Chicago that financed projects across the country, to Brickwell Community Bank in Woodbury, Minn., which had just a single branch and $72.6 million in assets.

Three others were taken over this month, including Warren Bank, a small lender just outside Detroit. Regulators swept into the offices on a recent Friday night after brokering a sale to Huntington Bancshares of Ohio, a regional bank with a big presence in Michigan.