Miles per hour is an imperial unit of speed expressing the number of statute miles covered in one hour. It is currently the standard unit used for speed limits, and to express speeds generally, in many countries throughout the world.
These include roads in the United Kingdom, the United States, American Samoa, the Bahamas, Belize, British Virgin Islands, the Cayman Islands, Dominica, the Falkland Islands, Grenada, Guam, Myanmar, The N. Mariana Islands, Samoa, St. Lucia, St. Vincent & The Grenadines, St. Helena, St. Kitts & Nevis, Turks & Caicos Islands, the U.S. Virgin Islands,Antigua & Barbuda (although km are used for distance), and Puerto Rico (same as former).
The kilometre per hour (American English: kilometer per hour) is a unit of speed, expressing the number of kilometres travelled in one hour. The unit symbol is km/h or km·h−1.
Worldwide, the km/h is the most commonly used unit of speed on road signs and car speedometers. Along with the kilowatt hour, km/h is the most commonly used metric unit based on the hour. Although the "hour" is not an SI unit, it is accepted for use with the International System of Units by the International Bureau of Weights and Measures (BIPM).