Aside from car accidents, which are indeed a problem, Montgomery County is about as safe a highly populated area as you'll find anywhere in the United States. The gang crime and robbery problems that plague the nation's capital simply do not spill across the district borders, with a robbery rate of just 100 per 100,000 residents in 2007. You might occasionally hear murmurs of Silver Spring or Wheaton having a crime problem, but this notion simply does not align with reality as shown by police statistics. Unless wandering alone late at night in an isolated part of a deserted downtown area, you are quite unlikely to become a victim of a crime.