The price of a first-class U.S. stamp increased three cents to 49 cents on Sunday.
It is the largest costumer postage rate increase in more than a decade, Time reported.
Other postage rates also have increased: It now costs 34 cents to mail a postcard, for example.
Two billion fewer pieces of mail were sent in 2013, Time said, and the U.S. Postal Service is struggling to make up for the lost revenue.
There’s one way around this and any future postage increases: Forever stamps, launched in 2007, have no price on them and are always valid, no matter what consumers paid for them.