A WALK from the history museum on the edge of St Louis’s verdant Forest Park, past grand faux-Tudor mansions on Lindell Boulevard, leads to the wealthy white neighbourhood of Central West End. Turn left on Euclid Avenue and you pass the Drunken Fish sushi restaurant, Golden Grocer Natural Foods, trendy espresso bars and Left Bank Books, displaying titles thoughtfully chosen by bibliophile shop assistants. Then these businesses suddenly stop, a block or so away from Delmar Boulevard. This is the city’s unofficial demarcation line...