The colonization movement began in 1816 as an antislavery response to the dilemma of what to do with free and freed blacks. Southerners believed that it was dangerous and ill-advised for free blacks to remain in the slave states. But blacks also posed a problem in the free states, who rather took a NIMBY stance. The only alternative some saw was gradual emancipation and colonization. The idea of colonization was not new–Thomas Jefferson and other Revolution-era leaders proposed colonization as a solution to the paradox of freedom and liberty in America.
James Gillespie Birney (1792-1857) was a Kentucky-born reformer and influential conservative abolitionist who graduated what is now Princeton in 1810. He began practicing law in 1814 and promptly entered Kentucky politics, but his ambitions soon took him to Alabama, where–unfortunately for his ambition–he opposed Andrew Jackson and championed liberal slave laws. He was involved in the American Colonization Society by 1826, and served as their agent in the southwest from 1832-33. He freed his own slaves in 1834, when he wrote this tract, in which he rejected gradualism and formally repudiated colonization. A year later, Birney proclaimed, “There will be no cessation of conflict until slavery shall be exterminated or liberty destroyed . . . liberty and slavery cannot both live in juxtaposition”
Thomas Wilson Dorr (1805-1854) was Birney’s contemporary, also a lawyer (he began practicing law in Rhode Island in 1827), and also a leading reformer–see http://www.dorrrebellionmuseum.org/dorr.htm.