Spring forward, Fall back. 

We know the routine well, but have you ever wondered why the United States uses Daylight Saving Time (DST)?

If you ask around, you'll hear some interesting theories:

...so kids don't have to catch the school bus in the dark?

        No.

...to save energy?

        Not really.

...to benefit farmers by giving them an extra hour of daylight?

        Not even close.

Turns out this sleep-cycle menace to society has a long, tortured history.

It Took a World War to Enact Daylight Saving Time

While some lore might attribute Daylight Saving Time's invention to Benjamin Franklin, it was actually Englishman William Willett who first campaigned for what he termed "summer time" so that more people would enjoy the earlier daylight between April and October.

Willett died in the midst of World War I in 1915 and one year later, England's adversary, Germany, instituted what we know as Daylight Saving Time (note the grammatically correct saving, not savings) as a way to conserve electricity. Great Britain quickly followed suit. In March 1918, the United States joined in and passed the Standard Time Act in order to implement DST as a wartime measure.

History of Daylight Saving Time in the United States

As for farmers, their schedules are dictated by the Sun, not the clock. In fact, farmers were largely opposed to DST during WWI as it presented inconveniences with regard to morning dew evaporation, hours for hired workers, and late-day cow milking. In 1919, agrarian interests led to a repeal of national Daylight Saving Time (including an override to President Woodrow Wilson's veto).

Following the repeal, many states and cities (including New York City and Chicago) continued to utilize DST. World War II ushered the return of national Daylight Saving Time, and three weeks after the war it was appealed once more.

Inconsistent adoption of Daylight Saving Time across states and municipalities resumed post-WWII. According to History.com, by 1965, Iowa alone had 23 different pairs of DST start and end dates.

In 1966, Congress passed the Uniform Time Act to bring order to the national hodgepodge of DST. While states could opt out of DST, the legislation required DST to start at 02:00 (local time) on the last Sunday in April and end at 02:00 on the last Sunday in October.

The Uniform Time Act was amended in 1986, moving the uniform start date to the first Sunday in April (effective 1987). The latest amendment, as part of the Energy Policy Act of 2005, moved the uniform start date for DST up by about a month to the second Sunday in March and extended the end date to the first Sunday in November (effective 2007).

Does Daylight Saving Time Save Energy?

The Energy Policy Act of 2005 also required the U.S. Department of Energy to report to Congress the impact of the DST extension by December 1, 2007 (strangely, a mere nine months after the statute took effect). The study, released in October 2008, reported the "total electricity savings of Extended Daylight Saving Time were about... 0.03 percent of electricity consumption over the year [2007]."

When it comes to energy considerations, Daylight Saving Time might even do more harm than good. The University of California Santa Barbara examined Indiana's move to statewide DST in 2006 and found that the savings in electric lighting was eclipsed by increased HVAC loads and led to a roughly 1-percent increase in residential electricity use.

What Purpose Does Daylight Saving Time Serve?

One could make the case that retail sector and recreational businesses may benefit from an extra hour of daylight early in the morning during the warmers parts of the year. Hence, commercial interests have championed Daylight Saving Time over the years.

However, many question the perceived value of DST. The Atlantic once referred to Daylight Saving Time as "the greatest continuing fraud ever perpetuated on American people."

Daylight Saving Time by Country

Considering all of the confusion in the U.S. over Daylight Saving Time, it likely comes as no surprise that the adoption of DST varies considerably throughout the world.