The price increase is part of a larger effort by the agency to solve its financial problems after losing nearly $16 billion in 2012.
The U.S. Postal Service has raised the price of its 'Forever' stamps by one cent to 46 cents.
A Forever stamp is valid for first-class postage, and it never expires or loses its value, even if the price of the stamp goes up. In 2012, the rate increased to 45 cents.
Other price changes include a one-cent increase for postcards, to 33 cents.
More price increases can be found here.
Postal Service head Patrick Donahoe said the agency lost around $15.9 billion last year.
The Associated Press contributed to this story.
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