Mattumassd- Dartmouth, MA has a population of about 25-40 African-Americans, in a town of about 31,000 residents.
http://www.town.dartmouth.ma.us/
There were 4 African-American students at Dartmouth High School with me, and probably about a handful more dispersed throughout the elementary and middle school level. New Bedford High School though, (our rivals, and neighbor to the east) is a different story. I believe their student population is 40-45% African-American.
So obviously, Dartmouth isn't a very diverse community. The southern part of town can get pretty snobby and uppity with their yachts and expensive cars. Houses in the "lower class" parts of town don't usually sell for less than $200,000, if that gives you a clue about how low "lower class" really is. The thing is, houses in Padnaram (the historic harbor village) can run anywhere from $750,000 to well into the millions if you want to live in an exclusive community with waterfront property, and your own personal dock/mooring.

Silly if you ask me!
Michael J. Fox, Ben Affleck, Matt Damon, and Geraldo Riveira have houses in Nonquitt...(one of those affluent, exclusive communitites

)