China, with a total area of 9.38 million square kilometres (3.62 million square miles) according to the World Bank, is the largest country to observe just one time zone: Beijing (or China) Standard Time. Despite spanning five geographical time zones, the country adopted a single time zone in 1949, at the behest of Communist Party Chairman Mao Zedong, in order to unify the nation and allow for a communal work schedule. In reality, many of the regions assume their own informal time zones – when it is midnight in Beijing, for example, the sun is only just setting in Xinjiang in the westernmost part of the country.
A time zone ideally spans 15 degrees of longitude and effectively represents the point at which the sun is at its highest in the sky at noon. With a west-to-east span of c.4,800 km (3,000 mi), China covers more than 60 degrees of longitude and therefore could have five time zones (UTC+5 to UTC+9), as it once did prior to Chairman Mao's decree, when it ranged from UTC+5.30 to UTC+8.30.
In second and third place are India (2.97 million km2) and Argentina (2.73 million km2).
