Prince George's County
Prince George's County, or more affectionately, PG, is best known as the wealthiest majority-black county in the U.S. It is home to both the main campus of the University of Maryland and a major NASA facility.
There is a pretty clear division between Northern PG County (northeast of D.C.) and Southern PG County (southeast of D.C.). The former is significantly more densely populated and wealthy than its poorer cousins to the south, which share more in common with their even poorer neighboring areas in southeastern D.C..
Prince George's County is known to have a higher than average crime-rate for the metro area. However, as in most places, most of the worst crime occurs between people who are already acquainted, or are associated with drugs.
In addition, Metro parking lots in Prince George's County, especially Greenbelt and New Carollton, have higher than average incidences of car break-ins; avoid leaving anything of value in sight when leaving your car in these parking lots.