A mile is a unit of length most commonly equivalent to 5,280 feet or 1,760 yards (about 1,609 metres). The mile of 5,280 feet is also known as the statute mile or land mile to distinguish it from the nautical mile of approximately 6,076 feet (1,852 metres exactly). There have also been many historical miles and similar units in other systems that may be translated into English as miles; they have varied in length from 1 to 15 kilometres. The exact length of the land mile varied slightly among English-speaking countries until the international yard and pound agreement in 1959 established the yard as exactly 0.9144 metres, giving a mile exactly 1,609.344 metres. The U.S. adopted this international mile for most purposes, but retained the pre-1959 mile for some land-survey data, terming it the U. S. survey mile. In the United States, statute mile normally refers to the survey mile, about 3.2 mm ( inch) longer than the international mile (the international mile is exactly 0.0002% less than the U.S. survey mile). While most countries replaced the mile with the kilometre when switching to the International System of Units, the international mile continues to be used in some countries such as Liberia, Myanmar, the United Kingdom and the United States. It is furthermore used in a number of countries with vastly less than a million inhabitants, most of which are US or UK territories, or have close historical ties with the US or UK: Am. Samoa, Bahamas, Belize, British Virgin Islands, Cayman Islands, Dominica, Falkland Islands, Grenada, Guam, The N. Mariana Islands, Samoa, St. Lucia, St. Vincent & The Grenadines, St. Helena, St. Kitts & Nevis, the Turks & Caicos Islands, and the U.S. Virgin Islands. The mile is even encountered in Canada, though this is predominantly in rail transport and horse racing, as the roadways have been metricated since 1977.