Reformers began working for the abolition of slavery in the earliest days of the American republic. By 1804 they had succeeded in the northern states and turned all their efforts to attacking slavery in the south and opposing its spread in the west. Postage rates decreased from the 1830s through the 1850s, allowing abolitionists to distribute literature cheaply via the post office. Many southerners regarded these mail campaigns as an attack, aided and abetted by the federal government.
The New Method of Sorting the Mail, As Practiced by Southern Slave-Holders, 1835
The Charleston, South Carolina post office was raided by a pro-slavery mob in July 1835. “U.S.M.” on the mail bag at lower left stands for U.S. Mail, and the mob is burning bundles of abolitionist newspapers—with the help of the city postmaster.