Black and Hispanic voters support marijuana legalization at a slightly lower rate than whites. But because black voters are overwhelmingly Democrat, and Hispanic voters are disproportionately so, that means they are far to the right of white democrats on the issue. 78% of democrats as a whole support marijuana legalization, versus 67% of black and 63% of Hispanic people. Because black and Hispanic people comprise roughly 35% of the party, the rest of the party (for the most part, whites) have to support legalization at 85%. So there is roughly 20% gap between white and black and Hispanic Democrats on legalization.
See: https://www.google.com/amp/s/www.pewresearch.org/fact-tank/2...