Kerry James Marshall: In the Tower

CHICAGO -- In Kerry James Marshall's 1994 painting "Great America," the centerpiece of an exhibit of the artist's work opening June 28 at the National Gallery of Art, four black figures are piled into a small boat that's part of an amusement-park ride. The figures are dark, almost silhouettes, and strangely unaffected by the light falling on the water around them, as if they're from some other picture altogether.