Alexander Crummell settled in Washington, D.C. in 1873 and became “missionary at large to the colored people.” He focused on founding and strengthening urban black congregations that would provide worship, education, and social services for their communities. In 1883 when the Southern Bishops proposed that all black congregations become separate missionary districts, Crummell organized the Conference of Church Workers Among the Colored People (succeeded by the Union of Black Episcopalians) in protest.
You can read more about Father Crummell at the Archives of the Episcopal Church.