Map of Malaria in the USA, 1870


Nat Torkington says,

Here is a Library of Congress map showing prevalence of Malaria throughout the United States in the 1870s. Astonishing how dangerous it was. In some places, it accounted for one-seventh of all deaths. People thought it was bad air (literally, "mal-" + "air"), figured out it was a parasite in the blood in the 1870s, but it wasn't until 1908 that a Cuban doctor made the connection with mosquitoes.

Incidentally, if you've ever wondered what the "ague" is that Shakespeare kept banging on about--it's what the English called malaria. It was widespread in the marshlands during Shakespeare's time. (via sciblogs)