Alexander Fulton founded which city that had a mild subtropical climate that was required for agricultural production using slave labor? 
Alexander Fulton (Louisiana): Alexander Fulton (died c. 1818) was a merchant, planter, and local politician originally from Washington, near Pittsburgh in western Pennsylvania, who in 1805 founded the city of Alexandria, Louisiana, which he named for himself. Plantations in the American South:  The mild subtropical climate, plentiful rainfall, and fertile soils of the American Southeast allowed large plantations to flourish; where large numbers of workers, usually Africans held captive for slave labor, were required for agricultural production.
Alexandria, Louisiana