How much mail is handled by the U.S. Post Office per day?

According to the Report of the Postmaster General, 106,311,062,000 pieces of mail traveled through the system in 1980.

On a given day, therefore, approximately 291,263,000 items passed through the country’s post offices.

What’s more, this prodigious amount of mail traveled through many fewer post offices than at the turn of the century.

In 1900, there were 76,688 post offices; in 1980, there were 30,326.