Each time zone differs from its neighboring time zones by 1 hour.

The United States has a vast territory from east to west, so the time zones in different States are different.

Similarly, China uses the national unified Beijing time.

The United States spans six time zones from the West Fifth District to the West Tenth District. Each time zone corresponds to a standard time. From east to west, it is Eastern Time (est, the fifth district in the west, including 19 states near the Atlantic coast and mainland, and Washington, D.C., the representative city is Washington), Central Time (CST, the sixth district in the west, including Chicago and New Orleans), Mountain Time (MST, the seventh district in the west) and Pacific Time (PST, the eighth district in the west, including the Pacific Ocean). According to the law of "early in the east and late in the west", each hour will be reduced. The so-called western time refers to Pacific time.