The scheduling of television programming in North America (namely the United States, Canada, and Mexico) must cope with different time zones. The United States (excluding territories) has six time zones (Hawaii–Aleutian, Alaska, Pacific, Mountain (including MST), Central and Eastern). Canada has five time zones (Mountain, Central, Eastern, Atlantic, and Newfoundland). Mexico has four time zones (Southeast, Central, Pacific, and Northwest). In addition, each country has further variation across these zones in the observance of daylight saving time. This requires broadcast and pay television networks in each country to shift programs in time to show them in different regions.
In Canada Broadcast networks Canadian broadcasting networks, with five time zones and a much larger percentage of their audience residing in the Mountain Time Zone than in the Central Time Zone, are sometimes able to avoid the issues that affect American programming by airing pre-recorded programs on local time. CBC Television and CTV created delay centres in Calgary in the early 1960s to allow programming to air in each time zone based on the region.
In order to protect local advertising revenue, the simsub rules allow broadcast stations to require feeds of U.S. broadcast stations on local pay television to be substituted with the Canadian station's signal if they are airing the same program. This can affect how commercial broadcasters schedule their programming outside of Eastern, Central, and Pacific Time areas: the Atlantic and Mountain time zones are one hour ahead of the U.S. stations historically carried on television providers in their respective markets (such as Boston in Atlantic Canada, and Spokane in Alberta), meaning that stations may air programs out of pattern in comparison to other markets to maximize simsub opportunities (such as an 8p.m. PT program airing at 9p.m. MT),
Saskatchewan does not observe Daylight Saving Time, officially observes Central Standard Time year-round. This matches Mountain Daylight Time when DST is in effect; networked stations generally follow the schedules of their sister stations in Manitoba year-round, except delayed by one hour.
Unlike in the United States, virtually all live events, including live entertainment shows and sports television, are simultaneously broadcast nationwide in Canada. For instance, live shows in Canada are aired to the entirety at the same time in all time zones based on Eastern time. Several live U.S. shows are also aired simultaneously in all of Canada, including for viewers on the Pacific Coast (unlike in the United States, where some viewers on the same side of the continent depend on tape-delayed broadcasts for some otherwise live events). Conversely, live shows aired in Canada are frequently televised simultaneously for some viewers in the U.S. with access to Canadian broadcast networks.
Cable and satellite channels The vast majority of specialty cable and satellite television channels in Canada each operate a single feed which is distributed in all time zones. This includes all French-language channels, as they predominantly serve Francophone areas of the country, mostly in Quebec (almost all of which observes Eastern Time). Even many long-standing specialty channels with a general entertainment format use a single national feed, though in many cases they will repeat core primetime programming three hours after first broadcast, such that programs can be promoted as airing at the same time in both the Eastern and Pacific time zones.
Some specialty channels do operate two separate broadcast feeds for Eastern and Western Canada. The Eastern feed airs programs on an Eastern Time schedule, while the Western feed airs the same programming on a three-hour delay. The separation between feeds is typically implemented at the border between Manitoba and Ontario, which may result in a program that airs at 10:00 p.m. Eastern Time in Ontario not airing in Manitoba until midnight CT (whereas an equivalent program in the U.S. would typically be available at 9:00 p.m. for Central Time viewers). However, one channel, the Aboriginal Peoples Television Network, implements the separation at the border between Manitoba and Saskatchewan.
Watershed and safe harbour The code of ethics of the Canadian Broadcast Standards Council (CBSC) enforces a watershed, in which programs that contain coarse or offensive language or sexually explicit material intended for adult audiences may only air in the late viewing period when children are less likely to be watching, defined as 9:00p.m. to 5:30a.m. nightly. This can be problematic if the same content is broadcast simultaneously nationwide, as a program airing at 9:00p.m. ET would air as early as 6:00p.m. PT in the west. Officially, the watershed rule is applied at the signal's origin.
PrideVision (now OUTtv) was particularly affected as, from its launch in 2001 until 2005, its format included more innocuous entertainment and lifestyle programming aimed at the LGBT community during the daytime and prime time, and hardcore pornographic content in the overnight hours. Due to content concerns, many television providers marketed PrideVision as a premium, adult channel, rather than a mainstream specialty channel. Shaw Communications frustrated the ability to access a nationally-distributed free preview of PrideVision upon its launch by requiring subscribers to specifically request it, and be charged a one-cent fee (which it did not require of the 39 other fledgling digital cable channels participating in the same preview); the CRTC sided with the network's owners, requiring Shaw Cable and Star Choice to carry the Pridevision preview without additional access requirements. The network's adult programming was later spun out into a second channel so that the parent network, relaunched as OutTV, could broadcast its entertainment and lifestyle programming across its entire broadcast day.
In the United States Time zone feeds With four time zones in the contiguous United States, American broadcast television networks generally transmit at least two separate feeds to their owned-and-operated stations and affiliates, as do cable/satellite channels: the eastern feed that is aired simultaneously in the Eastern and Central Time Zones, and the western feed that is tape-delayed three hours for those in the Pacific Time Zone. This ensures that a program, for example, that airs at 8:00 p.m. ET on the East Coast (7:00 p.m. CT) is also shown locally at 8:00 p.m. PT on the West Coast. Such a program may be advertised as "8/7c". Networks may also transmit a third feed specifically for the Mountain Time Zone, on which programs are usually broadcast on a one-hour delay from the Eastern Time Zone. Otherwise, some stations in the Mountain Time Zone use the western feed, while others get a mix of both the Eastern and Pacific feeds.
The Eastern Time Zone is commonly used as a de facto premier time for the United States as the region covered by the zone covers nearly half of the U.S. population and has the highest metropolitan area density within the country.Based on 2011 population estimates, 46% of the American population live in the Eastern time zone, 30% in the Central zone; 7% in the Mountain zone, and 17% in the Pacific zone. Network promotions typically advertise airtimes either on Eastern Time only or, more commonly, in conjunction with airtimes in the Central or Pacific Time Zones.
Network stations in the Alaska and Hawaii–Aleutian Time Zones that draw from the western feed utilize the local delay scheduling approach applied to affiliate stations in the Central and Mountain zone that receive their network's eastern feed. Daytime and prime access programming is transmitted simultaneously on network affiliates in the Pacific and Alaska Time Zones; stations in the Hawaii–Aleutian Time Zone transmit a secondary local feed, on which programs are usually broadcast on a two-hour delay from the Pacific Time Zone.
Broadcast television Effectively, the East, Mountain and West network feeds allow prime time on broadcast television networks to end at 10:00 p.m. Central, Mountain, Alaska and Hawaii–Aleutian, and 11:00 p.m. Eastern and Pacific. When it first expanded its programming into prime time in April 1987, Fox became the first major broadcast network in the U.S. to offer a common prime schedule; this type of scheduling subtracts an hour from the prime time schedule, reducing it to two hours on Monday through Saturdays and three hours on Sundaysending evening network programming earlier than NBC, CBS and ABC did and continue to do. (Fox did expand its Sunday prime time schedule into the 10:00 p.m. timeslot in September 1987, before giving back that hour to its stations in September 1993.) UPN and The WB followed the common prime scheduling model when they both launched in January 1995; the replacements for those networks, The CW and MyNetworkTV, similarly used that model upon their launches in September 2006.
In 2009, PBS began using Internet servers instead of separate feeds for time delaying of its programming to the network's member stations. The servers imitate a delayed program feed, broadcasting the program at the correct airtime as if it were being broadcast via satellite. This was done as PBS had upgraded its main program feed to high definition (or to widescreen digital at the very least) in December 2008, but satellite capacity allowed for only Eastern and Pacific time zone feeds, prompting the removal of the Central and Mountain time zone feeds and a shared feed for Alaska and Pacific time zones in February 2009, which created complaints from PBS stations.
Cable and satellite television Subscribers to cable or satellite television services may still only receive East Coast feeds for certain channels even if they reside on the West Coast. Providers in the Mountain Time Zone, Alaska and Hawaii may transmit either the Pacific Time Zone feed or the East Coast feed, depending on the service or channel. Some cable channels only offer one broadcast feed, where viewers see the same program in all time zones. For example, until it dropped the program in 2014, superstation-turned-basic cable channel WGN America (now NewsNation) telecast the noon (Central Time) newscast from WGN-TV in Chicago at 1:00 p.m. Eastern in Washington, D.C. and 10:00a.m. Pacific in Los Angeles.
Broadcasters offer East and West Coast feeds of some basic cable channels for viewing in all time zones. The usage of dual feeds of the same channel is a commonplace method for premium channels such as HBO, Cinemax, Showtime and Starz, in which the Pacific time zone feed of the primary channel is packaged with the East Coast feed of the main channel and the pay service's multiplex channels, if the premium channel has any. (MGM+ subverts this as its Eastern Time feed acts as the default main channel feed available to most contracted providers and its TV Everywhere and OTT streaming platforms, while its Pacific feed is mainly restricted to systems in the Western United States.) HBO maintains a separate Hawaii–Aleutian Time feed of its primary channel; the three-hour-delayed version of the Pacific Time feedwhich is exclusively carried by the state's dominant cable provider, Oceanic Spectrumis the only Hawaii-specific timeshift feed currently maintained by an American cable-originated network. (The state's other major cable provider, Hawaiian Telcom, transmits the Pacific Time feeds of all seven HBO channels, which Oceanic also packages with the main channel's Hawaii–Aleutian Time feed.)