A furlong is a unit of distance equal to one-eighth of a mile, or 220 yards. The word comes from Old English, meaning “furrow long”: the length of a furrow a team of oxen could plow before needing rest.

While most Americans today measure distances in miles, feet, and yards, furlongs still appear in horse racing. When you hear that a race is “six furlongs,” that means the horses will run three-quarters of a mile. The Kentucky Derby, one of America's most famous races, is ten furlongs, or one and a quarter miles.

Furlongs also show up in older literature and historical documents. In England, they were commonly used for centuries to measure farmland and roads. If you're reading a classic novel and encounter someone traveling “five furlongs to the village,” they went a little over half a mile.

The furlong reminds us that many measurement systems grew from practical human activities. Modern life has made furlongs mostly obsolete, but they survive where tradition matters: at the racetrack and in history books.