Central Time Zone (North America)

Central Time Zone (North America)
Name	Central Time Zone
Utc offset	−06:00
Utc offset DST	−05:00
Dst name	Central Daylight Time
Tz1	United States
Tz2	Canada
Tz3	Mexico

Contents

Definition and offset
Observance
History
Daylight saving time
Major metropolitan areas
See also

Central Time Zone (North America). The Central Time Zone is a time zone in parts of Canada, the United States, Mexico, Central America, some Caribbean islands, and part of the Eastern Pacific Ocean. It is six hours behind Coordinated Universal Time (UTC−06:00) during standard time and five hours behind (UTC−05:00) while observing daylight saving time. The zone is one hour ahead of the Mountain Time Zone and one hour behind the Eastern Time Zone.

Definition and offset

The Central Time Zone is geographically defined as the area between longitudes 82.5° West and 97.5° West. This places it six hours behind Greenwich Mean Time and Coordinated Universal Time. The United States Department of Transportation historically held authority over time zone boundaries within the United States. In practice, the zone's western boundary generally follows the border between Kansas and Colorado, while its eastern edge runs near the border of Michigan's Upper Peninsula and Wisconsin. The National Institute of Standards and Technology and the United States Naval Observatory are key institutions maintaining official time standards for the zone.

Observance

In the United States, the Central Time Zone is observed in all or parts of many states, including Alabama, Arkansas, Illinois, Iowa, Louisiana, Minnesota, Missouri, Mississippi, Oklahoma, Tennessee, Texas, and Wisconsin. In Canada, the provinces of Manitoba and Saskatchewan (except the city of Lloydminster) observe Central Time, along with parts of Nunavut and northwestern Ontario. In Mexico, this zone, known as *Zona Centro*, covers much of the country's interior, including Mexico City, Guadalajara, and Monterrey. Several Central American nations, including Guatemala, Honduras, and El Salvador, also fall within this zone.

History

The concept of standard time zones in North America was formally proposed following the Conférence internationale de l'heure in 1912. The Interstate Commerce Commission took over time zone management in the United States after the Standard Time Act of 1918 was passed by the United States Congress. This act also established daylight saving time, which was later repealed and reinstated multiple times, notably during World War II. The Uniform Time Act of 1966, signed by President Lyndon B. Johnson, created the modern framework for time observance. The boundaries of the Central Time Zone have been subject to local petitions and changes, such as those reviewed by the United States Department of Transportation.

Daylight saving time

Most regions within the Central Time Zone observe daylight saving time, shifting clocks forward one hour to Central Daylight Time (CDT) from the second Sunday in March to the first Sunday in November, as established by the Energy Policy Act of 2005. Notable exceptions include the Canadian province of Saskatchewan, which remains on Central Standard Time year-round, and the Mexican state of Sonora, which aligns with Mountain Standard Time and does not observe DST. The Navajo Nation, located within Arizona, does observe DST, creating a complex time picture in the region.

Major metropolitan areas

The Central Time Zone contains some of the largest population centers in North America. In the United States, these include Chicago, Houston, San Antonio, Dallas, Austin, Memphis, Milwaukee, and New Orleans. In Mexico, the massive Greater Mexico City area, Guadalajara, and Monterrey are key cities. Canadian metropolitan areas in the zone include Winnipeg in Manitoba and Thunder Bay in Ontario. Other significant centers are Minneapolis–Saint Paul, St. Louis, Kansas City, and Oklahoma City.