WASHINGTON (AP) ― Regulators on Friday shut down four small banks in three states, boosting to 55 the number of U.S. bank failures this year.

The overall pace of closures, however, has slowed this year as banks work their way through piles of bad debt. A slow, but improving U.S. economy also has helped stem the number of bank casualties this year. By this time last year, regulators had closed 96 banks.

The Federal Deposit Insurance Corp. seized High Trust Bank in Stockbridge, Ga., One Georgia Bank in Atlanta, First Peoples Bank in Port St. Lucie, Fla., and Summit Bank in Prescott, Ariz.

The action brings to 16 the number of lenders to collapse this year in Georgia. In Florida, the tally is now seven, while in Arizona it’s now two.

High Trust had about $192.5 million in assets and $189.5 million in deposits, while One Georgia had about $186.3 million in assets and $162.1 million in deposits. First Peoples had about $228.3 million in assets and $209.7 million in deposits.

Summit had $72 million in assets and $66.4 million in deposits.

Ameris Bank, based in Moultrie, Ga., agreed to assume all of the deposits from the two Georgia banks and buy essentially all of their assets.

Premier American Bank, National Association, of Miami, is assuming all the deposits of First Peoples and is purchasing essentially all of its assets.

The Foothills Bank in Yuma, Ariz., agreed to assume all of Summit’s deposits and acquire essentially all its assets.

The failures are expected to cost the deposit insurance fund $129.1 million, combined.

High Trust Bank had two branches and First Peoples had six, while One Georgia Bank and Summit each had a single branch.

In 2010 regulators seized 157 banks, the most in a year since the savings-and-loan crisis two decades ago. The FDIC has said 2010 likely would mark the peak for bank failures.

There were 140 bank failures in 2009, costing the insurance fund about $36 billion.

The failures last year cost around $21 billion, a lower price tag because the banks involved were smaller on average. Twenty-five banks failed in 2008, the year the financial crisis struck with force; only three were closed in 2007.

From 2008 through 2010, bank failures cost the fund $76.8 billion. The deposit insurance fund fell into the red in 2009. With failures slowing, the FDIC’s deficit narrowed in the first quarter of this year; it stood at about $1 billion as of March 31.

Depositors’ money ― insured up to $250,000 per account ― is not at risk, with the FDIC backed by the government. That insurance cap was made permanent in the financial overhaul law enacted last July.

The number of banks on the FDIC’s confidential “problem” list edged up to 888 in January through March from 884 as of Dec. 31. The 888 troubled banks is the highest number since 1993, during the savings-and-loan crisis. But that doesn’t mean the pace of bank failures is likely to accelerate again because, historically, only 19 percent of the banks on the “problem” list actually fail.