Standards: Daylight Saving Time (DST)

Daylight Saving Time (DST) is a widely used system that adjusts the official local time forward from the official standard time during summer months, usually by one hour.

The  Energy Policy Act of 2005 changed the start and end dates of Daylight Saving Time in the United States. As of 2007, DST begins on the second Sunday in March and ends on the first Sunday in November. The U.S. Department of Energy (DOE) is studying the impact of this DST extension, and the  U.S. Congress retains the right to revert to the previous DST schedule if the study shows it does not produce a significant savings of energy.

Use of Daylight Saving Time in the United States, is governed by the Uniform Time Act of 1966. This Act provides a standard for establishing the dates when DST begins and ends in the U.S., while allowing local exemptions from its observance. States wishing to be exempt from DST may pass a law exempting the entire state. The states of Arizona and Hawaii do not observe DST. However, the Navajo Indian Reservation in Arizona does. In addition, American Samoa ,  Guam , the  Northern Mariana Islands ,  Puerto Rico , and the  U.S. Virgin Islands  do not observe DST.

Approximately  70 countries observe DST .

Additional Resources:

• Daylight Saving Time Rules
• Time Exhibits
• The Seasons: Spring, Summer, Fall and Winter
• Standards: Leap Year

Standards: Daylight Saving Time (DST)

Daylight Saving Time (DST)  is a widely used system that adjusts the official local time forward from the official standard time  during summer months, usually by one hour.

The  Energy Policy Act of 2005  changed the start and end dates of Daylight Saving Time in the United States. As of 2007, DST begins on the second Sunday in March and ends on the first Sunday in November. The  U.S. Department of Energy (DOE)  is studying the impact of this DST extension, and the  U.S. Congress retains the right to revert to the previous DST schedule if the study shows it does not produce a significant savings of energy.

Use of Daylight Saving Time in the United States, is governed by the Uniform Time Act of 1966. This Act provides a standard for establishing the dates when DST begins and ends in the U.S., while allowing local exemptions from its observance. States wishing to be exempt from DST may pass a law exempting the entire state. The states of  Arizona  and  Hawaii  do not observe DST. However, the Navajo Indian Reservation in Arizona does. In addition,  American Samoa ,  Guam , the  Northern Mariana Islands ,  Puerto Rico , and the  U.S. Virgin Islands  do not observe DST.

Approximately  70 countries observe DST .

Additional Resources:

• Daylight Saving Time Rules
• Time Exhibits
• The Seasons: Spring, Summer, Fall and Winter
• Standards: Leap Year