The U.S. Postal Service said on Friday it plans to raise the price of a first-class postage stamp to 58 cents, from 55 cents, to offset falling revenues as volumes drop.

In the past 10 years, mail volume has sunk 28%, USPS said in a statement, and is continuing to fall.

Prices for postcards, international letters and other services will increase as well, effective Aug. 29.