Neck and Neck

A straightforward image from horse racing, dating to the early 1800s. A "neck" was already an established unit for measuring a horse's lead over its rivals, the length of a horse's head and neck. When two horses were so evenly matched that their necks stayed level with each other the whole way down the course, spectators described the race as "neck and neck." By the early 19th century, the phrase had already jumped from the racetrack into general use for any tight, too-close-to-call contest between people.