The Eastern Time Zone (ET) is a time zone encompassing part or all of 22 states in the eastern part of the contiguous United States, parts of eastern Canada, the state of Quintana Roo in Mexico, Panama in Central America, and certain Caribbean and Atlantic islands, along with certain countries and parts of countries in South America. Places that use Eastern Standard Time (EST) when observing standard time (autumn/winter) are five hours behind Coordinated Universal Time (UTC−05:00). Eastern Daylight Time (EDT), when observing daylight saving time (spring/summer), is four hours behind Coordinated Universal Time (UTC−04:00). In the northern parts of the time zone, on the second Sunday in March, at 2:00 a.m. EST, clocks are advanced to 3:00 a.m. EDT leaving a one-hour "gap". On the first Sunday in November, at 2:00 a.m. EDT, clocks are moved back to 1:00 a.m. EST, thus "duplicating" one hour. Southern parts of the zone (Panama and the Caribbean) do not observe daylight saving time. The largest city in the Eastern Time Zone is New York; the New York metropolitan area is the largest metropolitan area in the zone.