Which US States Do Not Observe Daylight Saving Time?

Daylight Saving Time (DST) shifts clocks forward in spring and back in fall, but not all U.S. states participate. Travelers and residents often wonder which states skip the seasonal change. The answer is straightforward: only two states—Arizona and Hawaii—do not observe DST. Understanding why these states remain on standard time year‑round helps clarify scheduling, travel plans, and legal requirements across the country.

The two states generally associated with no DST

Arizona and Hawaii are the only U.S. states that do not observe Daylight Saving Time. Arizona’s decision dates back to the 1960s, when the state legislature passed a law to remain on Mountain Standard Time (MST) throughout the year. Hawaii, located far west in the Pacific, opted out in 1967 to avoid the inconvenience of shifting clocks for its small population and unique geographic position. The result is that, unlike the rest of the country, both states keep the same time offset from Coordinated Universal Time (UTC) all year, simplifying timekeeping for residents and visitors alike.

Why most of Arizona stays on standard time

Arizona’s refusal to adopt DST stems from its extreme summer heat. The state’s climate, characterized by temperatures frequently exceeding 100°F, makes the extra daylight hours in the evening less useful and can increase energy consumption for cooling. By staying on standard time, Arizona reduces the need for air conditioning during the hottest part of the day, helping to lower electricity demand. Additionally, the state’s economy, which relies heavily on tourism and agriculture, benefits from predictable scheduling without the biannual clock change. The decision has been reinforced by public opinion and state law, ensuring that Arizona remains on Mountain Standard Time for the entire year.

States That Do Not Change Clocks for Daylight Saving Time — What three US states do not observe daylight saving time? Source: www.youtube.com

How the Navajo Nation exception works

The Navajo Nation spans parts of Arizona, New Mexico, and Utah. Unlike the rest of Arizona, the Nation observes daylight saving time (DST) to align with neighboring states and federal schedules. The decision is rooted in economic and logistical considerations: many businesses and transportation services operate on DST schedules, and the Nation’s own government agencies coordinate with federal agencies that follow DST. The Navajo Nation’s observance is codified in the Navajo Nation Code, which explicitly states that the Nation will adopt DST in accordance with the Uniform Time Act of 1966. This means that residents in the Navajo Nation’s Arizona portion set their clocks forward in spring and back in fall, while those in the rest of Arizona keep standard time year‑round. The exception is applied uniformly across the Nation’s three-state footprint, ensuring consistency for commerce, education, and emergency services. The practice has been in place since the 1970s and remains a unique feature of U.S. time‑keeping.

Why Hawaii does not change clocks

Hawaii’s decision to stay on standard time year‑round stems from its geographic latitude and economic priorities. Located near the equator, the state experiences minimal variation in daylight hours across seasons, reducing the perceived benefit of DST. The state legislature has repeatedly voted against adopting DST, citing studies that show limited energy savings and potential disruptions to tourism and business operations. Hawaii’s tourism industry, which relies on predictable schedules for flights and hotel bookings, finds the extra hour of daylight in the evenings less valuable than the consistency of a single time zone. Additionally, the state’s infrastructure and transportation systems are designed around a single time standard, simplifying coordination across its islands. The Department of Transportation and the National Institute of Standards and Technology (NIST) recognize Hawaii’s choice, and the state remains exempt from federal DST mandates. This consistent time policy supports Hawaii’s unique cultural and economic landscape.

US territories that also do not observe DST

The United States has several territories that, like the states of Arizona and Hawaii, do not observe daylight saving time. The most prominent example is the Commonwealth of Puerto Rico, which remains on Atlantic Standard Time (AST) year‑round, staying two hours ahead of Eastern Standard Time. This policy aligns with the territory’s preference for a consistent schedule and avoids the biannual clock changes that can disrupt business and daily life. Another territory that does not observe DST is the U.S. Virgin Islands, which also stays on AST throughout the year. The U.S. territories of Guam, the Northern Mariana Islands, American Samoa, and the U.S. Minor Outlying Islands follow their respective local time zones without any daylight saving adjustments. These territories maintain a fixed offset from Coordinated Universal Time (UTC) and do not participate in the federal DST schedule, ensuring uniformity for residents and visitors alike.

How to check time when traveling between observing and nonobserving areas

When traveling between a state that observes daylight saving time and one that does not, it is essential to verify the current local time before departure. A reliable method is to consult the U.S. Department of Transportation’s official time zone maps, which indicate the presence or absence of DST in each jurisdiction. Additionally, the National Institute of Standards and Technology (NIST) provides a comprehensive database of time zone offsets, including historical changes. Travelers can use these resources to calculate the time difference by adding or subtracting the appropriate number of hours. For example, if you depart from Phoenix, Arizona (which does not observe DST) to New York City (which does observe DST), you must account for the fact that Phoenix remains on Mountain Standard Time year‑round, while New York shifts between Eastern Standard Time and Eastern Daylight Time. Checking a reputable world clock application or the official NIST time service before the trip can prevent missed appointments and ensure accurate scheduling.