Claiming his place as the 109th mayor of New York City, Bill de Blasio delivered an inaugural address on Wednesday that focused on the issue of inequality, promising that the attention he gave to the subject when he was running for office was not merely campaign rhetoric. Outside City Hall, in front of an audience that included members of his family, luminaries like Bill and Hillary Rodham Clinton and hundreds of ordinary New Yorkers, Mayor de Blasio spoke of the city’s history of embracing liberal causes, and he laid out a mayoralty that emphasized social and economic justice. “We are...