Encouraging the emigration of freed slaves to an asylum outside the boundaries of the United States became one part of attempts to end slavery in the United States. In 1789 James Madison, who became head of the American Colonization Society after leaving the presidency, endorsed an African colony as “a great encouragement to Manumission.… the best hope yet presented to putting an end to the slavery in which not less than 600,000 unhappy Negroes are now involved.”