Louisiana ranks fourth in the U.S. in crude-oil production and second in natural gas. Louisiana also ranks second nationally in crude-oil refining capacity. Petrochemical plants line the Mississippi River from New Orleans—the country's busiest port—to Baton Rouge, and the production of chemicals is the state's leading manufacturing activity. Tourism is the second most important industry. Vibrant New Orleans preserves its Creole heritage in the architecture and foods of the French Quarter. Lafayette, the heart of Cajun country, is home to descendants of the Acadians who were expelled from Canada in the mid-18th century.