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Why is a mile such an odd number of feet - 5,280? In fact, until Elizabethan times in England, a mile was 5,000 feet. The length was based on a Roman mile of 1,000 "double steps." But Queen Elizabeth I thought the mile should be evenly divisible by furlongs (a furlong is 220 yards, or 660 feet). So in 1593, Parliament passed a law extending the mile by 280 feet, making it eight furlongs. A furlong (short for "furrow long") was reportedly the distance a horse could pull a plow before it had to rest. But why lengthen the mile? Why not shorten the furlong? At the time, land deeds were recorded in furlongs. Changing the furlong would have confused land ownership. The length of a mile wasn't as critical then.
Source: 'Just Curious About History, Jeeves,' by Erin Barrett and Jack Mingo (Pocket Books, 2002); The Straight Dope (www.straightdope.com); www.wikipedia.org.