The story
Founded by Lysander Spooner in 1844.1
Spooner started the service out of frustration with exceedingly high postal rates. At the time, it cost 18 3/4 cents to send a letter from Boston to New York and 25 cents to send one from Boston to Washington, DC. A letter sent from Boston to Albany, New York, written on a 1/4-ounce sheet of paper and carried by the Western Railroad, cost 2/3 as much as the freight charge for carrying a barrel of flour the same distance.
Spooner's justification was that the Constitution provided for a government-run postal service, but did not exclude others from engaging in the same business. Spooner dropped his rates even lower, delivering many letters for free. This competition dropped prices dramatically with postage of 6 1/4 cents per each half-ounce and stamps 20 for a dollar. Deliveries were made twice daily between New York City and Philadelphia. The US Government tried to lower prices by threatening railroads to withdraw business. However, the U.S. Government challenged Spooner with legal measures whereby Spooner was initially vindicated. In fact, the U.S. Circuit Court expressed doubt that the U.S. had the right to monopolize the transportation of mail.
Congress eventually forced him to cease operations in 1851 by legislating a US monopoly.
From Wikipedia’s article on American Letter Mail Company, shared under CC BY-SA 4.0.4