What caused the rapid decline in the volume of first-class mail? The price of sending a piece of mail became too expensive for most Americans.

Americans decided that they reliec too heavily on the USPS to send and receive correspondence, so they stopped using
their services.

In 2007, the economy went over a financial cliff and people stopped using the USPS.

The ability to communicate digitally caused a change in people's behavior. they no longer had to send correspondence by
mail.