All postage rate information courtesy of the United States Postal Regulatory Commission.
History of United States Postage Rates
| Date Effective | First Ounce Rate | Additional Ounce | Postcard Rate |
| July 1, 1845 | .05 per half ounce (under 300 miles) | ||
| July 1, 1851 | .03 per half ounce (under 3,000 miles) | ||
| March 3, 1863 | .03 per half ounce | .03 per half ounce | |
| March 3, 1883 | .02 per half ounce | .02 per half ounce | |
| July 1, 1885 | .02 | .02 | |
| November 3, 1917 | .03 | .03 | |
| July 1, 1919 | .02 | .02 | |
| 1926 | .02 | .02 | .01 |
| July 1, 1919 | .02 | .02 | |
| July 6, 1932 | .03 | .03 | .01 |
| January 1, 1952 | .03 | .03 | .02 |
| August 1, 1958 | .04 | .04 | .03 |
| January 7, 1963 | .05 | .05 | .04 |
| January 7, 1968 | .06 | .06 | .05 |
| May 16, 1971 | .08 | .08 | .06 |
| March 2, 1974 | .10 | .10 | .08 |
| September 14, 1975 | .10 | .09 | .07 |
| December 31, 1975 | .13 | .11 | .09 |
| May 29, 1978 | .15 | .13 | .10 |
| March 22, 1981 | .18 | .17 | .12 |
| November 1, 1981 | .20 | .17 | .13 |
| February 17, 1985 | .22 | .17 | .14 |
| April 3, 1988 | .25 | .20 | .15 |
| February 3, 1991 | .29 | .23 | .19 |
| January 1, 1995 | .32 | .23 | .20 |
| January 10, 1999 | .33 | .22 | .20 |
| January 7, 2001 | .34 | .21 | .20 |
| July 1, 2001 | .34 | .23 | .21 |
| June 30, 2002 | .37 | .23 | .23 |
| January 8, 2006 | .39 | .24 | .24 |
| May 14, 2007 | .41 | .17 | .26 |
| May 12, 2008 | .42 | .17 | .27 |