Across the country, the income gap between blacks and whites remains wide, and nowhere more so than in Manhattan. But just a river away, a very different story is unfolding. In Queens, the median income among black households, nearing $52,000 a year, has surpassed that of whites in 2005, an analysis of new census data shows. No other county in the country with a population over 65,000 can make that claim. The gains among blacks in Queens, the city’s quintessential middle-class borough, were driven largely by the growth of two-parent families and the successes of immigrants from the West Indies....