In the study I heard about from a family member it correlates strongly up to a threshold, say $90,000 for a family of 3-4 living in the midwest (ex-Chicago, etc.), but thereafter increasing income doesn't increase happiness (and possibly erodes it).
Yes, what has been found is that anything below $60,000 is strongly correlated with unhappiness, but it flattens out above 60 annually. This was in a TED talk, probably one by Hans Rosling.
