John Osborne and James W. Gerencser, eds., "James Miller McKim," Dickinson Chronicles, http://chronicles.dickinson.edu/encyclo/m/ed_mcKimJM.htm.
His ministry gave way to his involvement in the abolition movement in 1833, when he attended the Philadelphia Conference which formed the American Anti-Slavery Society. A year later, in a town not supportive of the movement, McKim delivered Carlisle’s first anti-slavery speech at his church and started the Carlisle Anti-Slavery Society. In 1836, McKim, recruited by Theodore Weld, began his career as a full-time abolitionist and as an agent for the American Anti-Slavery Society. He attended the first Pennsylvania Anti-Slavery Society meeting in Harrisburg in 1838. In 1840 he moved to Philadelphia to become the corresponding secretary of the Society and the editor and manager of its publication, the Pennsylvania Freeman. As such, he became an influential supporter of the underground railroad organizations centered in Philadelphia assisting in the many court cases that emerged after the passage of the Fugitive Slave Law.
In 1859, he and his wife attended the execution of John Brown at Harpers Ferry and assisted Mrs. Brown in bringing her husband's body home. During the Civil War, McKim founded the Philadelphia Port Royal Relief Committee to help provide for the liberated slaves of Port Royal. The organization became statewide in 1863 as the Pennsylvania Freedman’s Relief Association. He also became actively involved in the authorizing and the recruiting of African-American units to the Union Army. Two years later, McKim moved to New York City to become the first secretary of the new American Freedman’s Union Commission, which operated until 1869. McKim also helped to found The Nation, a New York newspaper produced to support the interests of the newly freed men and provided Wendell Garrison the position of editor.
McKim married Sarah Allibone Speakman on October 1, 1840 and had two natural children, Charles Follen and Lucy; the couple also adopted McKim’s niece. Lucy McKim later married Wendell Phillips Garrison, son of William Lloyd Garrison, while the adopted niece became William Garrison’s second wife. James Miller McKim died on June 13, 1874 in Orange, New Jersey. He was sixty-three years old.