Nearly two-thirds of Philadelphia's residents are nonwhite and 53 percent are women, but you wouldn't know it from a visit to a city construction site. Despite decades of official hand-wringing over the lack of diversity in city trade unions, it's still mostly white men who rivet the steel, pour the concrete, and install the shiny glass facades on our new buildings. In 2008 — the last time anyone was able to pry any numbers from union leaders — just 10 percent of their members were African American.