"Daylight Saving Time (DST) is a period of the year between spring and fall when clocks in most parts of the United States are set one hour ahead of standard time. The time period for DST begins on the second Sunday in March and ends on the first Sunday in November. The beginning and ending dates are set in statute. Congressional interest in the potential benefits and costs of DST has resulted in changes to DST observance since it was first adopted in the United States." - Congressional Research Service