Port facilities along the deep, broad Delaware River led to a boom in shipbuilding during World Wars I and II. The first nuclear-powered merchant ship, the Savannah, was built in Camden. On the cultural side, poet Walt Whitman—whose unfettered, subjective style revolutionized poetic expression in the mid-19th century—lived his last years in Camden. The tomb of the good gray poet is in Harleigh Cemetery on Haddon Avenue.