The time zones observed by the 48 states use generic names, without highlighting the difference between DST and standard time designations. The DST is observed in all of the contiguous states except Arizona (observed only in the Navajo Nation). Washington, Nevada, California, and parts of Oregon and Idaho observe Pacific Time Zone (UTC-07:00) while the states straddled by the Rocky Mountains and Great Plains’ western quarter have Mountain Time Zone (UTC-06:00). The second time zone on the contiguous US is the Central Standard Time (UTC-05:00), observed fully by ten states and partly by the other ten states occupying the Mississippi Valley, Gulf Coast, and parts of the Great Plains. However, Indiana, Florida, Kentucky, Tennessee partially use this time zone. All or most of the 23 states in the eastern US, including those on the Atlantic coast, observe Eastern Time Zone (UTC-04:00). These states fall within four time zones. The contiguous US comprises 48 states located within continental North America. The Department of Transportation regulates the DST and time zone boundaries in the US. The contiguous US observes four time zones, while Hawaii, Alaska, and each of the five territories has its time zone. From west to east, the nine US time zones are Chamorro Standard Time (UTC+10), Samoa Standard Time, Hawaii-Aleutian Standard Time (HST), Alaskan Standard Time (AKST), Pacific Standard Time (PST), Mountain Standard Time, Central Standard Time, Eastern Standard Time (EST), and Atlantic Standard Time (AST). By Law, the United States of America and its territories use nine time zones, with most of the county observing DST (daylight saving time) for much of spring, fall, and summer months.

Time zone map america