Several historic graveyards in Charleston feature areas and stones marked by the term "strangers", referrring to visitors from other areas of the world who flocked to the city in colonial and anteellum era for business and pleasure. Charleston was the fourth largest city in America in 1800, and richest per capita, so business people came from as far as London, Liverpoo, Boston and New York. Riches also brought such pleasantries as thoroughbred horse-racing and international stars for local Charleston theater, which further attracted people from other parts of the world. Typically, they were not accustomed to Charleston's sub-tropical climate, which in the 18th and 19th century could be lethal with yellow fever. Charlestonians usually developed an immunity to this disease if they lived past age 13 or 14, but for many strangers, a visit sometimes was the end of the road, and so many died that yellow fever was nicknamed stranger's fever.