Do blacks have higher risk for strokes?

Generally yes: When looking at populations of african americans, they tend to have risk factors for stroke such as hypertension and diabetes mellitus that are less well controlled than a similar population of whites. Some of this is due to insurance or the lack of, and all other other ills of medicine. Equalize the risk factors between whites and blacks, the risk for stroke is likely very similar.

Stroke risk : African Americans are at twice the risk of having a stroke at least. No one knows for sure why that is the case, although it may be related at least in part to their higher incidence of hypertension.