Research by Raj Chetty, Nathaniel Hendren, Maggie Jones, and Sonya Porter from the Equality of Opportunity Project suggests that black boys who grow up in rich families are still much more likely to fall into lower income levels than white boys who grow up in equally rich families. The shift from low income to higher levels also appears to be a greater challenge, which makes closing the gap that much harder.
Emily Badger, Claire Cain Miller, Adam Pearce, and Kevin Quealy for The Upshot cover the data extensively with a series of charts, driven visually with a particle-based Sankey diagram (above). The individual points provide a vehicle to show variation over aggregates.
You can grab the aggregated data from the Equality of Opportunity Project. Here’s the research paper in full (pdf) if you’re interested. And if you’re interested in the Sankey implementation.