It happens more frequently in off-year elections when turnout is lower. Sussex VA (58% black) voted 52-48 for McDonnell in 2009 as did Brunswick VA (57% black) by 50-49.
It seems like Sussex, and less so Brunswick, are rural counties with sizable prisons that affect the data the same way that Angola does in Louisiana.
https://vadoc.virginia.gov/facilities/eastern/sussex1/https://vadoc.virginia.gov/facilities/eastern/brunswick/I didn't know about Brunswick but I remembered Sussex because there was some year when it was one of the fastest growing counties in Virginia because the prison had just opened.
(on edit: here's the story, Sussex County was the fastest growing county
in the entire U.S. because of the prison population.
http://www.ncpa.org/sub/dpd/index.php?Article_ID=10430)
