In the United States, there were 30,456 banks in 1921, but there were only 4,377 at the end of 2020, a drop of 86%, reports William R. Emmons, the Federal Reserve Bank of St. Louis' assistant vice president and chief economist in the Supervision Division.

According to Emmons, some new banks are merging, while some are becoming charters. The decline started during the Great Depression in 1929. The total number of U.S. banks by the end of 1933 was 14,207, less than half the number in 1921.

During the next quarter-century, the decline was significantly slower and primarily the result of mergers, Emmons wrote. Despite rebounding to 14,496 banks by 1984, the number has fallen by 70% since then, with 10,000 banks disappearing since then, although never 600 in a year.

Since the 1980s, there have been a high number of mergers between banks, and bank failures and new bank entries have almost stopped entirely since 2015.

Emmons wrote that commercial banks are still suffering a slow but steady decline. Bank failures have declined, but the rate of bank chartering has declined to insignificance, and bank mergers remain historically high on a percentage basis.

The number of completed bank mergers reached 173 by the end of  November this year, which represents 4% of all banks. The FDIC reports nine new commercial banks, no bank failures and four voluntary bank liquidations in 2021.