Daylight Savings Time
Daylight saving time has been a staple of the U.S. calendar for the better half of the last century. The U.S. is not the only country, nor the first, to observe daylight saving. Around 70 countries observe daylight saving time, mostly in the Northern Hemisphere.
Learn the history of Daylight Savings time here: https://www.timeanddate.com/time/dst/history.html