The United States is divided into six time zones, which are used throughout the country with some exceptions. The time zones were first established in 1883 and have undergone changes since then. The U.S. Department of Transportation (DOT) has been responsible for governing time zones in the country since 1967.

The four standard time zones in the contiguous United States are:

• Pacific Time (PT)

• Mountain Time (MT)

• Central Time (CT)

• Eastern Time (ET)

In addition to these four time zones, there are six corresponding Daylight Saving Time (DST) zones. Alaska and Hawaii also have their own time zones, which do not observe DST.

The time zones in the United States are defined by the Code of Federal Regulations (CFR), Title 15, Chapter 6, Subchapter IX - Standard Time. The regulations outline the specific dates and times when clocks can be adjusted for daylight saving purposes.

Interestingly, there is a theoretical 12th time zone called 'Anywhere on Earth' (AoE) that includes Howland Island and Baker Island, which are the world's westernmost landmasses in relation to the International Date Line. However, this time zone is not officially recognized by the U.S. government.

The use of time zones in the United States can be complex, with some states observing DST while others do not. For example, Hawaii and most of Arizona do not observe DST, while some parts of Indiana also opt out of the practice.

In conclusion, the time zone map of the United States is composed of six main time zones, with some exceptions and variations depending on the state or territory. Understanding these time zones and their corresponding DST periods can be crucial for both personal and professional purposes.

Time zone map of us