[First Presidency, letter to Marion G. Romney]
Your letter of June 5 is in hand, in which you set out the case of Sister Carrie [?] Millgate Marshall, which raises the question of conferring the Priesthood upon male members of the Church who have a trace of negro blood in their veins though they themselves show apparently no signs of it.
This matter has received in the past repeated consideration at the hands of the Brethren and always with an answer to the effect that a person with any negro blood in his veins may not receive the Priesthood. The question will continue to stand thus until another ruling is made.
[First Presidency, Letter to Marion G. Romney, as quoted in Minutes of the Apostles of The Church of Jesus Christ of Latter-day Saints, 1910-1951, Privately Published, Salt Lake City, Utah 2010]