The American Shorthair is a breed of cat. This breed was first used as ship's cats that sailed from Europe to North America with early settlers. They kept the ships free of mice and rats and protected the food and cargo. Even the Mayflower carried several cats to hunt the ship’s rats, in 1620. The cats who were still alive after landing in the New World had kittens. Over time, the breed changed so the cats could survive better in their new land and climate.