With the trade of sugar, rum, and African slaves in the islands that form a perimeter around the Gulf of Mexico, the broad expanse of water known as the Caribbean ringed what came to be known as the South.

Today concise political boundaries separate the coasts of the American South from the multicultural worlds that dominate the islands. Yet all anecdotal evidence suggests far greater ties. One listens to the reggae in the streets of New Orleans or to the rumba in Atlanta. One notes the moans of the blues in the cafes of Veracruz and watches Major League games in which young Dominican...