A chart of Imperial and customary units. We use Imperial (colonial) measures. "Customary" = common for the United States. Truth. I was so confused trying to understand why we use 5,280 feet = 1 mile, I gave up.
"It originated in the Roman mille passuum, a thousand paces, or more precisely, a thousand strides. Each pace consisted of five Roman feet, giving us a mile of 5,000 feet. Since the Roman foot (the pes) was smaller than today’s foot, the Roman mile was about nine-tenths the length of our mile. "
Since the Tudors lengthened these measurements and created the modern day "foot", a mile --
"Unfortunately, the English also had the idea, for reasons we needn’t go into here, that a mile consisted of eight furlongs. The furlong, short for “furrow-long,” is said to have been the distance a horse could pull a plow before having to rest. Its length was a matter of confusion for quite a spell, but by the 16th century folks generally agreed that it consisted of 40 rods of 16-1/2 feet each, or 660 feet in all — and of course eight furlongs was 5,280 feet. "