It was 1907 when Englishman William Willett proposed advancing clocks 20 minutes each Sunday in April and reversing them in September. He said daylight made people more cheerful.
Some jokers said maybe the freezing point should be set at 45 degrees so people would feel warmer in winter.
For most of the early 19th century, America had a confusing mix of time zones. Each community could decide what time it was. The state of Wisconsin had 38 time zones. In 1883, the railroad standardized time zones for itself, but that didn't matter much to people who weren't traveling.
Early supporters of clock turning included Marcus Marks, president of the borough of Manhattan. He said people would stay out later, play more games and spend more money, making everyone healthier and wealthier.
"Summer Time" was also supported by chambers of commerce, restaurants, the American Medical Association, insurance companies and labor unions.
All of this might not have been enough, but World War I changed everything. The government said fewer lamps lit in the evening would mean more fuel for the war effort, and on March 31, 1918, America turned its clocks ahead one hour.
But in 1918, many Americans didn't usually bother with clocks, or even own them at all. On farms, people rose at sunrise and retired after twilight.
During World War II, clocks were set ahead year round. But from 1945 to 1966, states and cities could choose if and when to observe daylight savings time. One 35-mile strip between West Virginia and Ohio had seven time zones.
The Uniform Time Act of 1966 standardized daylight savings time, though states can pass laws to exempt themselves. Areas near large cities can opt to stay in the city's time zone even if they are in a different state.
Arizona (except for the Navajo Nation) and Hawaii, are now the only states that don't observe daylight savings time.