During the Civil War, the U.S. Treasury received a check for $1,500 from a private citizen who said he had misappropriated government funds while serving as a quartermaster in the Army. He said he felt guilty.

“Suppose we call this a contribution to the conscience fund and get it announced in the newspapers,” suggested Treasury Secretary Francis Spinner. “Perhaps we will get some more.”

Ever since then, the Treasury has maintained a “conscience fund” to which guilt-ridden citizens can contribute. In its first 20 years, the fund received $250,000; by 1987 it had taken in more than $5.7 million. One Massachusetts man contributed 9 cents for using a damaged stamp on a letter, but in 1950 a single individual sent $139,000.

In order to encourage citizens to contribute, Treasury officials don’t try to identify or punish the donors. Most donations are anonymous, and many letters are from clergy, following up confessions taken at deathbeds.

Many contributions are sent by citizens who have resolved to start anew in life by righting past wrongs, but some are more grudging. In 2004, one donor wrote, “Dear Internal Revenue Service, I have not been able to sleep at night because I cheated on last year’s income tax. Enclosed find a cashier’s check for $1,000. If I still can’t sleep, I’ll send you the balance.”