How many time zones does China officially use?

China spans a stretch of longitude wide enough for five natural time zones, and until 1949 it used them. The new government replaced the lot with a single standard time set to the capital, and the whole country has run on it since. The reasoning was political and administrative: one clock for one nation, with railways, broadcasts and government offices all synchronised, and no ambiguity about when a national announcement takes effect. The cost falls on the far west. In Xinjiang, at the country's western edge, the official clock puts sunrise well into the morning and sunset late at night by local solar reckoning, so people there informally shift their schedules by a couple of hours, and some keep an unofficial local time alongside the national one. It is a good illustration that time zones are administrative choices rather than natural facts, which is also why some countries use offsets of half or three-quarters of an hour.

China also does not observe daylight saving, so the offset stays the same all year.