The South has a wet subtropical climate due to moisture from the Gulf of Mexico and Caribbean, which along with rich coastal plain soils supports agriculture. Cities grew on the Fall Line, where rivers ended and waterfalls began, because river transportation terminated and textile factories exploited the cotton industry. Oil production in Texas and Gulf states spawned petrochemical industries, though declining oil is replaced by growing petrochemical and rubber production. The South attracted industrial migration with newer, more efficient plants, cheaper land and labor costs due to fewer unions, fueling economic development. Tourism also thrives due to the climate. The population is richly diverse, including Mexicans, Cubans, and African Americans.