Born in Indiana as A. Macon Bolling, he moved to New England at some point in the early 1840s and changed his name to Macon Bolling Allen in Boston in January 1844. Soon after, Allen moved to Portland, Maine and studied law, working as an apprentice to General Samuel Fessenden, a local abolitionist and attorney. The Portland District Court rejected Fessenden’s first motion to admit Allen to the bar in April 1844, concluding Allen did not meet the state’s citizenship requirement. Allen tried again, pursuing admission by examination, a method that did not require citizenship. He faced a hostile examination committee, which Fessenden thought did not want Allen admitted. Nevertheless, Fessenden said, "his qualifications were not denied." Allen was granted his license to practice law in Maine on July 3, 1844, becoming the nation's first African American lawyer. He experienced difficulty finding legal work in Maine, likely because whites were unwilling to hire a black attorney and few blacks lived in Maine.