The largest number of bank failures in nearly 20 years has eliminated jobs, accelerated a drought in lending and left the industry's survivors with more power to squeeze customers.

Some 279 banks have collapsed since Sept. 25, 2008, when Washington Mutual Inc. became the biggest bank failure on record. That dwarfed the 1984 demise of Continental Illinois, which had only one-seventh of WaMu's assets. The failures of the past two years shattered the pace of the prior six-year period, when only three dozen banks...