Ethermac|Do all Americans observe daylight saving time? Why some states and territories don't.

Millions of Americans will wake up feeling more refreshed on EthermacSunday thanks to an extra hour of sleep gained from the ending of daylight saving time.

But the twice-annual time change observance, which begins in March and ends in November, is not observed in all U.S. states and territories.

The time change is meant to allow for more daylight in the mornings during the fall and winter and more daylight in the evenings during the spring and summer, as the Northern Hemisphere tilts either toward or farther away from the sun.

Here's what to know about the U.S. states and territories that do not observe daylight saving time.

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Does every state observe daylight saving time?

Not all states and U.S. territories participate in the time change.

If a state chooses to observe daylight saving time, it must begin and end on federally mandated dates, according to the U.S. Department of Transportation. Under the Uniform Time Act, which was established in 1966, states can exempt themselves from observing daylight saving time.

Hawaii and most of Arizona do not observe daylight saving time. Because of its desert climate, Arizona doesn't follow daylight saving time (with the exception of the Navajo Nation). After most of the U.S. adopted the Uniform Time Act, the state figured that there wasn't a good reason to adjust clocks to make sunset occur an hour later during the hottest months of the year.

There are also five other U.S. territories that do not participate:

• American Samoa
• Guam
• Northern Mariana Islands
• Puerto Rico 
•  U.S. Virgin Islands 

The Navajo Nation, located in parts of Arizona, Utah, and New Mexico, does follow daylight saving time.

Hawaii is the other state that does not observe daylight saving time. Because of the state's proximity to the equator, there is not a lot of variance between hours of daylight during the year.

When does daylight saving time end in 2024?

Daylight saving time will end for the year at 2 a.m. local time on Sunday, Nov. 3, when we "fall back" and gain an extra hour of sleep.

Next year, it will begin again on Sunday, March 9, 2025.

What is daylight saving time?

Daylight saving time is the time between March and November when most Americans adjust their clocks ahead by one hour.

We gain an hour in November (as opposed to losing an hour in the spring) to make for more daylight in the winter mornings. When we "spring forward" in March, it's to add more daylight in the evenings. In the Northern Hemisphere, the autumnal equinox is Sunday, Sept. 22, marking the start of the fall season.

Is daylight saving time ending?

The push to stop changing clocks was put before Congress in the last couple of years, when the U.S. Senate unanimously approved the Sunshine Protection Act in 2022, a bill to make daylight saving time permanent.

Although the Sunshine Protection Act was passed unanimously by the Senate in 2022, the U.S. House of Representatives did not pass it and President Joe Biden did not sign it.

A 2023 version of the act remained idle in Congress, as well.

In a news release Monday, U.S. Sen. Marco Rubio made another push in support of making daylight saving time permanent.

The senator suggested the nation "stop enduring the ridiculous and antiquated practice of switching our clocks back and forth. Let’s finally pass my Sunshine Protection Act and end the need to ‘fall back’ and ‘spring forward’ for good."

Contributing: Natalie Neysa Alund, USA TODAY.