Claudia Sitgraves has produced an interesting research summary on "The Benefits of Marriage for African American Men" for the Institute for American Values. She reports that married black men work more than single black men, and make more, too -- 14 - 18% more in earnings. This is not so surprising - married men usually work more, and harder, and thus earn more than single men in all groups.
The surprising finding came from a longitudinal study (by the late Steve Nock) the followed black men through various stages of the life cycle. He found that the married men started earning more than most single men, as expected. He also found that those single men who nonetheless started earning at high levels were less likely to marry than their lower-earning single counterparts. The conventional wisdom is that higher-earning single men are better marriage prospects. It may be the case the higher-earning single black men are so sought after that they can reap the benefits of marriage without marrying.
This finding is a little disheartening for marriage proponents. It is worth following up.