Despite geographically crossing five time zones, all of China uses the same time zone. Why?

As anyone who has ever looked at a map of the world knows, China is one of the world’s largest countries. From the coastline on the Pacific Ocean in the East to the outskirts of the Central Asian region in the West of China, a very broad expanse of land is contained. Were it to use time zones, as most nations do, it would cover five of them.

Hong Kong, Macau, and Taiwan are also lumped in with the rest of China and use the same time zone. All of China is eight hours ahead of Coordinated Universal Time. The Chinese do not observe daylight savings time either.

Let’s say you are planning on doing some traveling, or maybe you’re just curious about the time in other places. If you live in the Eastern Time Zone in North America, China is 13 hours ahead of you. In the Western U.S. And Canada, the time in China would be 16 hours in the future. Folks in the UK are eight hours behind China.

China was moved to a single time zone by the communists, in order to "promote national untity".

(Source)