Life expectancy is the ultimate measure of a neighborhood’s well-being, and many of the map’s bright red splotches designating the lowest rates in the city line up neatly with the places where Monday night’s violence occurred. “Health equity is a civil rights issue,” Dr. Leana Wen, Baltimore’s health commissioner, said in an interview. “We’re often told we grow up in the land of two Baltimores. Life expectancy differs by 20 years, depending on which city block you happen to be born in.”