Paul Stewart, who founded Denver's Black American West Museum in 1971, died at his Aurora home Thursday, according to the Denver Post.
Known as a storyteller, collector and the man who set out to prove that black cowboys existed, Stewart was 89.
Stewart's wife Johnnie "J'Mae" Stewart told the Post that he stopped undergoing dialysis last week after six years of treatment:
"He decided he did not want to suffer that process anymore and made a conscious decision, knowing the consequences," she said. "He said if God woke him up in the morning then that would be because he was OK, and if he didn't he was fine with that because he would be with Christ."
A historian and an author, Stewart dedicated his life to documenting the involvement of African Americans in the American West.
"African Americans play a very important part, but it wasn't in the history books," Stewart told CPR News in 2014. "And my main object is to make people aware that we were here and we did contribute to the history."