An abbreviation for miles per hour, the primary means of measuring speed of land vehicles under the old English (Imperial) system of measurement. Still used occasionally in Canada and the United Kingdom, although the official system outside the U.S. remains the metric system. Some handy conversion factors: 1 MPH = 2.16 m/s = 1.61 km/hr.1
Most places in the U.S. have a speed limit on highways of 55 or 65 MPH, equivalent to around 100 km/hr. Near the Canadian border, signs give the speed limit in both systems. Most cars sold in the U.S., regardless of their country of origin, have markings for both MPH and km/hr on their speedometers.
Can be written in all capital letters or all lowercase letters (mph).
1 Thanks to pi for the conversion to m/s.