Spring is approaching and our days are continuing to get "longer." Daylight hours for most of us will begin even earlier in the evening when we move our clocks ahead an hour to begin daylight saving time (March 9). Many people will change their clocks, but do they know why?

Daylight saving time was primarily started in the United States for the sake of conserving energy. The Standard Time Act was passed in 1918, which officially established time zones and incorporated daylight saving months into federal law. This was during World War I, when national efforts were made to conserve materials for the war effort. It was believed that if daytime hours could correspond better with natural light, fewer tasks would need to be done at night. Homes would need to use less energy to stay lit.

After the war, daylight saving time was revoked. When food conservation became mandatory in the United Sates during World War II (rather than just being encouraged as it was in WWI), daylight saving time was once again instated. Referred to as "War Time," it spanned from early February until the end of September.

After the war "Peace Time" was back in effect and the issue of daylight saving time was handled on a local level. This led to a great deal of confusion as different locations were constantly operating at different times. The Uniform Time Act was passed in 1966 to solve the problem. States were given the option to opt out of daylight saving time if they passed proper ordinances.

With daylight saving no longer a federal mandate, some states have chosen not to observe it. Among the states that don't currently participate in daylight saving are Arizona and Hawaii, with several U.S. territories choosing not to follow it as well. Arizona has such intense heat in daylight hours that it's not considered a benefit for its residents to be out for as much of it as possible.

As for Hawaii, its location closer to the equator gives them more consistent "days" year round. They wouldn't be gaining, or losing, many daylight hours by observing the clock change.

Daylight saving time (also called "summer time") is observed in many countries all over the world, though the time frame for it varies. In the United States it ran from the last Sunday in April to the first Sunday in October until the Energy Policy Act was passed in 2005. As of 2007, daylight saving now runs from the second Sunday in March until the first Sunday in November.

The argument continues over whether or not daylight saving time makes enough of an impact on energy costs to be worth observing.