The Underground Railroad saw an explosion of activity in the 1840s. In 1842, the Supreme Court ruled in Prigg v. Pennsylvania that states did not have to aid in the return of runaway slaves.

In an attempt to appease the South, Congress passed the Compromise of 1850, which revised the Fugitive Slave Bill. The law gave slaveowners "the right to organize a posse at any point in the United States to aid in recapturing runaway slaves. Courts and police everywhere in the United States were obligated to assist them" (Blockson, 11). Private citizens were also obligated to assist in the recapture of runaways. Furthermore, people who were caught helping slaves served jail time as well as pay fines and restitution to the slaveowner.

Click below to see posters from this era.

• "$150 REWARD… TOM…", a reward poster for an escaped slave.
• "PUBLIC NOTICE … MARTIN BARKER", another reward poster.
• "CAUTION COLORED PEOPLE OF BOSTON…", an abolitionist poster trying to prevent the recapture of escaped slaves in the North.