That Vox article is being misleading when they frame it based on "reported using the drug in the last year" because doing coke once on New Years is a lot different that doing coke daily. Looking at the daily use stats their statement that "In 2007, black people were 3.6 times more likely to be arrested for drugs than white people." doesn't seem so extremely disproportionate considering the daily usage is in some cases 3x as much. Very dishonest article.
Sorry for double post, it wouldn't let me edit the other one for more clarity.
Based on your comment, it seems like you haven't done much independent reading on this topic...
Here's a place to start: https://www.vox.com/2014/7/1/5850830/war-on-drugs-racist-min...