CDT はどこで使われている？
世界で今日中部夏時間が観測される場所。
Central Daylight Time (CDT) is the summer (DST) clock for the U.S. Central time zone. The Central time zone reaches well beyond the U.S. — but DST observance varies by country.
United States
CDT is the dominant summer clock for ~30% of the contiguous U.S. by area: Texas (most), the upper Midwest, the Mississippi corridor and most of the Great Plains. See our full state list.
Mexico
Until 2022, Mexico observed daylight saving in most of the country, where CDT-equivalent times were used in central states (Mexico City, Guadalajara, Monterrey). Since the 2022 reform, most of Mexico stays on standard time year-round (UTC −6), so CDT alignment is no longer year-round.
Central America
Some Central American countries — Honduras, Nicaragua, Costa Rica, El Salvador, Guatemala, Belize — sit in the Central time zone but generally do not observe DST, so they stay on UTC −6 year-round.
Canada
Manitoba and most of Saskatchewan use Central Time, but Saskatchewan does not observe DST (so it effectively stays on CST/UTC −6 year-round, which equals CDT/UTC −5 for half the year). Manitoba does observe DST and switches to CDT.