Definitions

zone out

Central Time Zone (North America)

The Central Time Zone observes standard time by subtracting six hours from UTC during standard time (UTC−6) and five hours during daylight saving time (UTC−5). The clock time in this zone is based on the mean solar time of the 90th degree meridian west of the Greenwich Observatory.

In the United States and Canada, this time zone is generically called Central Time (CT). Specifically, it is Central Standard Time (CST) when observing standard time (Winter), and Central Daylight Time (CDT) when observing daylight saving (Summer). In Mexico this time is known as the Central Zone.

The zone is one hour ahead of the Mountain Time Zone and one hour behind the Eastern Time Zone.

Regions using Central Standard Time

Canada

The Canadian province that observes Central Time in its entirety:

The Canadian provinces and territories that observe Central Time in part with another time zone (other time zone):

United States

The states of the United States that observe Central Time in their entirety:

The states of the United States that observe Central Time only in part with another time zone: Part in Mountain Time

Part in Eastern Time

The exact specification for the location of time zones and the dividing line between zones is set forth in the Code of Federal Regulations at 49 CFR 71.

Mexico

Most of Mexico belongs to the Central Time Zone, with the six northwestern-most states being the exception: Baja California Sur, Chihuahua, Nayarit, Sinaloa, and Sonora follow UTC−7, while Baja California follows UTC−8.

The states of Mexico that observe Central Time in their entirety:

The states of the Mexico that observe Central Time only in part with another time zone (other time zone).

  • Nayarit just the Bahia de Banderas municipality uses the Central time zone.

Central America

UTC−6 is also observed in the Central American countries of:

Other regions

In South America, this zone includes the Ecuadorian province of Galápagos.

In Oceania, the Chilean Easter Island also belongs to this time zone.

Central Daylight Time

Daylight saving time is in effect in much of the time zone between mid-March and early November. The modified time is called Central Daylight Time (CDT) and is UTC−5. In Central America Nicaragua and Guatemala observe this change. Saskatchewan, Sonora and Galápagos do not observe the change, remaining on Standard Time year round. One reason that Saskatchewan does not take part in the time change is that geographically, most of the province should be placed in the Mountain Time Zone. To avoid this, they have moved onto "permanent" daylight saving by being part of the Central Time Zone. The only exception is the region immediately surrounding the Saskatchewan side of the biprovincial city of Lloydminster, which has chosen to use Mountain Time with DST, synchronizing its clocks with those of Alberta.

In some areas, starting in 2007, the local time changes from CST to CDT at 02:00 LST to 03:00 LDT on the second Sunday in March and returns at 02:00 LDT to 01:00 LST on the first Sunday in November. Mexico decided not to go along with this U.S.-led change and observes DST from the first Sunday in April to the last Sunday in October.

Broadcasting concerns

Due to the structure of broadcasting networks in the United States (mostly television, but to a lesser extent radio as well), prime time programming is aired simultaneously in the Eastern and Central Time zones, which accounts for lines such as "tonight at 8/7 Central" on many network promotional ads. As a result, morning programming lineups designed for East Coast viewers may start too early for viewers in the Midwest and the central South; hence, they are tape-delayed to air at 7:00 am Central (except when breaking news happens or special occasions such as the Macy's Thanksgiving Day Parade, which airs at 9:00 a.m. Eastern / 8:00 a.m. Central, pushing back the morning shows to air live at 6:00 a.m. Central).

Also, an hour of syndicated programming time (between 7:00 p.m. and 8:00 p.m. in the Eastern Time Zone) is lost since network prime time starts at 7:00 p.m. Central, forcing TV stations to choose between airing their 6:00 p.m. newscast and a program, or airing shows in 'blocks' preferred by syndicators (for example, Wheel of Fortune and Jeopardy! together, or Entertainment Tonight and The Insider). Many stations in the Central Time Zone tend to air one or both parts of the syndicated block at 5:00 p.m. or even earlier. The most common set of programming chosen by the big three television networks (ABC, CBS, and NBC) is to air a newscast at 5:00 p.m., national news at 5:30 p.m., local news at 6:00 p.m., and syndicated programming at 6:30 p.m. Some stations even show a newscast from 6:00 to 7:00 p.m. Another more recent dilemma of the 7:00 p.m. prime time start is that a combination of longer commutes and work hours than in the past have caused many people to not come home from work until after 7:00 p.m., cutting into the potential ratings of shows that start at this time. Of course, the reverse is also true, as simultaneous broadcasts offer viewers the chance to watch "prime time television" without having to stay awake until 11:00 p.m.

Similarly, media coverage of New Year's Eve celebrations in New York City often leave the Central Time Zone out. Late Night with Conan O'Brien, though produced in New York, when broadcast on New Year's Eve (as it does not air on weekends) takes advantage of its later time slot (11:35 p.m. Central) to lampoon this inconsistency and produce its own New Year's countdown for television viewers in the Central Time Zone, although most Central Time local network affiliates usually broadcast Conan after covering their own regional New Year's Eve celebrations. In some locations, New York's New Year's Eve celebration might be repeated or delayed one hour to correspond to the Central Time zone.

Interestingly, U.S. broadcast networks do tape delay in the other two continental U.S. time zones for prime-time programmes except during sporting events and other selected live events such as election night and Academy Awards. The Mountain Time Zone is tape-delayed one hour and the Pacific Time Zone three hours from original broadcasts, so that shows match the broadcast times of the Central and Eastern Time Zones respectively (i.e. prime time begins at 7:00 p.m. MT and 8:00 p.m. PT following the same order of programming as the other two time zones). In order to keep up with these differences in time zones, most general-entertainment cable networks offer 2 feeds, one for viewers in the Eastern and Central time zones and another for the Mountain and Pacific time zones.

Canadian broadcasting networks, with 5½ time zones to span and a larger percentage of its audience residing in the Mountain Time Zone than in the Central Time Zone (which only has one significant metropolitan area (Winnipeg, Manitoba), sometimes are able to avoid these issues by airing prerecorded programs on local time (except Newfoundland time), although adjustments are often still made, particularly on private networks (mainly due to the influence of U.S. television). This is particularly a problem in Saskatchewan as Central Standard Time is used year round, choosing not to change to daylight saving time during the summer. While Saskatchewan, Manitoba and parts of northwestern Ontario share the same clock setting during the winter season, Saskatchewan and Alberta share the same clock setting during the summer season, despite the fact that Alberta is in the Mountain Time Zone. Schedules must be adjusted for the summer season.

The problem is largely moot in Mexico and other parts of Latin America because of the lack of significant other time zones.

Alphabetical list of cities and metropolitan areas

References

Sources

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