There may have been dark skinned people in the Americas, but they were NOT black.
There is NO African DNA found in any of the indigenous populations anywhere in the Americas. That's a proven fact.
Green et al (2000) is a study of "African" ADMIXTURE in Mexico.
The "admixture" originates with the "African slaves" and not from African Americans from the United States
Recently, Lisker et al. (1996) compiled admixture estimates, using data derived from classical genetic systems reported in previous studies in Mexico. African or European admixture was identified in all regions and groups analyzed.
Even relatively isolated Native American populations showed some degree of African or European admixture when classical genetic systems were used with the trihybrid model (Lisker et al. 1996).
(Green et al 2000)
mtDNA Affinities of the Peoples of North-Central Mexico
Where Did Mexico's Blacks Go?