The Postal Service has published biographies of two former postmasters general — Charles Wickliffe, who served from 1841 to 1845, and Cave Johnson, who served from 1845 to 1849.
Wickliffe, the 11th postmaster general, was nominated by President John Tyler. He got Congress to enact the Postal Act of March 3, 1845, which set postage rates to 5 cents for letters traveling less than 300 miles and 10 cents over that distance, and limited the franking privilege to top federal officials.
Johnson, who succeeded Wickliffe, was postmaster general when Congress authorized the use of stamps. He also brought mail service to newly annexed Texas and launched the first mail service to the West Coast.
The Wickliffe and Johnson biographies are available in the postal history section of usps.com.
