Beginning Sunday, January 22, it will cost more to mail first class letters, postcards and packages within the US. The cost to mail a first class letter will be 45 cents, an increase of 1 cent. According to the USPS, this is the first increase since May 2009. The cost of mailing a postcard will be 32 cents, an increase of 3 cents. This is the second increase for postcard postage in less than a year; in April 2011, the USPS boosted the postcard stamp price from 28 cents to 29 cents. You will also pay more to send letters to Canada, Mexico and other international destinations. Click here for more information on all the postal increases.