As of August 2014, the most recent postage rate increase for a one-ounce first-class stamp was implemented on Jan. 26, 2014. The $0.03 increase brought the price up to $0.49.
1863 is the first year the postal service started charging stamp prices by the weight of the letter rather than the miles the letter was to travel to its destination. From that date through August 2014, there have been only 29 changes in the rates for a first class stamp. These include a temporary increase to $0.03 from $0.02 because of World War I. As of August 2014, most increases have occurred infrequently, although the rate increased almost as frequently as once a year from 2006 to 2014.