• Reports of check fraud have steadily risen since 2020, with stimulus checks becoming a target.

• There were 680,000 reports of check fraud in the US in 2022, compared to 350,000 in 2021.

• Scamming operations are sophisticated, multi-person schemes that banks are monitoring more closely.

Don't put checks in the mail, the US Postal Service is warning. Scammers are stealing more of them than ever — draining bank accounts and causing big headaches for banks and account holders.

Banks issued roughly 680,000 reports of check fraud last year, up from 350,000 reports in 2021. And the US Postal Inspection Service reported roughly 300,000 complaints of mail theft in 2021, more than double the prior year's total.

Early in the pandemic, government relief checks became an attractive target for criminals. The problem has only gotten worse and postal authorities and bank officials are warning Americans to avoid mailing checks if possible, or at least to use a secure mail drop such as inside the post office.

Check usage has been in decline for decades as Americans have largely switched to paying for their services with credit and debit cards. Americans wrote roughly 3.4 billion checks in 2022, down from nearly 19 billion checks in 1990, according to the Federal Reserve. But the average size of the checks Americans write rose from $673 in 1990 — or $1,602 in today's dollars — to $2,652 last year.

"Despite the declining use of checks in the United States, criminals have been increasingly targeting the US Mail since the COVID-19 pandemic to commit check fraud," the US Financial Crimes Enforcement Network wrote in an alert sent in February.

Checks are still frequently used by small businesses. Eric Fischgrund, who runs FischTank PR, a 30-person public relations firm in New York, had about 15 checks that were being mailed to him from clients stolen after they all went through the same Postal Service distribution center. Ten of them were successfully cashed by criminals.