To given you an idea of racism in the 1920's, Birth of a Nation premiered in 1915 and went on to sell a zillion tickets. Not only was there racism in this day and age, it was overt and unabashed. These were the days when racial purity mattered. These were the days when boxing colluded to keep out black boxers and Negros were fully excluded from baseball. Racism was the legal framework of the United States.
In Double Jack, I chose to apply racism as invisible to my main character. He saw Negros, interacted with them, accepted them in their station, and never once questioned whether any of it was right. He never once saw the rules as wrong. You, as a reader, I hope, see and recognize the racism for what it is. You may not know what their story is, but you know there's a story there.
Even the word that I use for Black Americans is the word of the age. Negro.
I avoided 'nigger'. It was period, but I never ran into a place where the word found appropriate expression. My grandfather used the word all the time. "That's what they're called!" he complained when he learned that people didn't like the word. My personal belief is that Sloe Joe should have used that word carelessly. It wasn't a cruel word to him, it was just a fact. But for us, it's not a fact, it's a cruel word. I think that Jack accepted it as a cruel word as well, so when he wrote down his memoir, he excised it from Joe's vocabulary. Joe wasn't cruel, but he was a product of his age.