The hard part about that is how race and class tend to be the same thing, especialyl in urban environs.
class NEEDS to be represented more in the US, but it isn't.... partly because everyone sees themselves as Middle Class... plus the complete blurring of the lines of blue and white collar and their respective tradional class idenities muddies things further (i.e. is a teacher who makes 35,000 a year less working class than a landscaper who makes 55,000?)
it depends where you are, as well...
i have a friend from East Boston, a working class Italian neighborhood in Boston, who got a scholarship to go to high school in D.C. and he said the first thing he noticed was that the town was divided into basically:
rich whites
poor blacks
wheras Boston, has PLENTY of poor whites in South Boston, Dorchester, Charlestown, etc etc etc...
(which is why the whole busing thing in the 70's was so horrible... poor whites from southies fighting with poor blacks from roxbury and it's not as if either of them had a pot to piss in...)
but, towns like boston, philly (kensington, yo), there are large working class (and working poor) white neighborhoods...
when i lived san diego, for every working class black or latin neighborhood, there was a white equivilant (remember, this is where Steinbeck's Oakie's ended up... good town to buy C&W records!)...
so, i wouldn't say the race/class thing is THAT hard fast of a rule... which i always thought was the problem with affirmitive action, i feel like it should have done on an economic, rather than a racial basis... i grew with a latin girl whose father was an astronaut and it bugs me to think she would get a slot in life somewhere quicker than the irish kid who's dad was an alcoholic truck driver... as i believe Jim Goad once said, the problem with affirmitive action is it punishes the children of the white share croppers rather than the children of the slave owners...
edit: decent explaination of southie busing riots, for brits and other non-bostonians:
http://www.hcs.harvard.edu/~fup/password/southboston.html