This tells me you're unaware of the fact that Joseph Smith did provide the priesthood to a handful of black members, and that the church was racially integrated all the way through. Smith's 1844 presidential platform even included a plan by which the government would raise money so that it could pay slave-owners to free their slaves.
Smith did indeed try to racially integrate the church, whatever his personal views on blacks might have been. The exclusion went in place under Brigham Young, but even then it wasn't a total exclusion. As it was, though, even though the US government forced Utah to accept "slave" status in order to keep an equal number of slave and free places going, Utah's laws concerning slave ownership were so extreme in nature that it was often cheaper to free one's slaves and hire servants.
I've not seen a lot of primary source documentation from Young himself, but I personally question if a good chunk of his prohibition didn't have anything to do with what happened in Missouri; the church being so welcoming to free blacks was one of the major sticking points between the members and the locals.
Yep--there were 2 black priests--Praise the LORD!
Over the past two centuries, the relationship between
black people and Mormonism has a history that includes both official and unofficial discrimination and more recently it includes increased outreach and involvement. Since the earliest decade of the church
Black Mormons have been members of the LDS Church. While at least two black men held the priesthood in the early church, from the mid-1800s until 1978,
The Church of Jesus Christ of Latter-day Saints (LDS Church) had a policy which prevented most men of
black African descent from being ordained to the church's
lay priesthood and barred black men and women from access to its temples.
Under the temple and priesthood restrictions before 1978, black members of African descent could not be ordained to offices in the Priesthood nor could they participate in
temple ordinances besides baptisms for the dead. For a time in the 1960s and 1970s, they were not even allowed to perform
baptisms for the dead. For men and boys beginning at the age of 12 in the LDS church, priesthood ordination is required in order to hold
leadership roles, perform baptisms, bless the
sacrament, and give other blessings. Since black men of African descent could not hold the priesthood, they were excluded from holding leadership roles and performing these rituals. Temple ordinances are necessary for members who wish to receive the
endowment and
marriage sealings which are necessary for
exaltation, and most black members could not enjoy these privileges during their lifetimes. Church leaders taught that these restrictions were commanded by God. In 1978, the First Presidency and the Twelve, led by church president
Spencer W. Kimball, declared they had received
a revelation that the time had come to end these restrictions. After this revelation, people of African descent could hold priesthood offices and could be granted temple admittance. Since that time due to the policy change and increased outreach the number of black members in the LDS church has growth rapidly, especially in Africa.
The priesthood of most other Mormon denominations, such as the Community of Christ, Bickertonite, and Strangite, have always been open to persons of all races. 
