Television in the United States had long been dominated by the
Big Three television networks, the
American Broadcasting Company (ABC),
CBS (formerly the Columbia Broadcasting System) and the National Broadcasting Company (
NBC); however, the
Fox Broadcasting Company (Fox), which launched in October 1986, has gained prominence and is now considered part of the "Big Four". The Big Three provide a significant number of programs to each of their affiliates, including
newscasts, prime time,
daytime and
sports programming, but still reserve periods during each day where their affiliate can air
local programming, such as local news or
syndicated programs. Since the creation of Fox, the number of American television networks has increased, though the amount of programming they provide is often much less: for example,
The CW only provides fifteen hours of primetime programming each week (along with three hours on Saturdays), while
MyNetworkTV only provides ten hours of primetime programming each week, leaving their affiliates to fill time periods where network programs are not broadcast with a large amount of syndicated programming. Other networks are dedicated to specialized programming, such as
religious content or programs presented in languages other than English, particularly Spanish. The largest television network in the United States, however, is the Public Broadcasting Service (
PBS), a non-profit, publicly owned,
non-commercial educational service. In comparison to the
commercial television networks, there is no central unified arm of broadcast programming, meaning that each PBS
member station has a significant amount of freedom to schedule television shows as they consent to. Some public television outlets, such as PBS, carry separate
digital subchannel networks through their member stations (for example,
Georgia Public Broadcasting; in fact, some programs airing on PBS were branded on other channels as coming from GPB Kids and
PBS World). This works as each network sends its signal to many local affiliated television stations across the country. These local stations then carry the "network feed", which can be viewed by millions of households across the country. In such cases, the signal is sent to as many as 200+ stations or as little as just a dozen or fewer stations, depending on the size of the network. With the adoption of
digital television, television networks have also been created specifically for distribution on the digital subchannels of television stations (including networks focusing on classic television series and films operated by companies like
Weigel Broadcasting (owners of
Movies! and
Me-TV) and
Nexstar Media Group (owners of
Rewind TV and
Antenna TV), along with networks focusing on music, sports and other niche programming).
Cable and satellite providers pay the networks a certain rate per subscriber (the highest charge being for
ESPN, in which cable and satellite providers pay a rate of more than $5.00 per subscriber to ESPN). The providers also handle the sale of
advertising inserted at the local level during national programming, in which case the broadcaster and the cable/satellite provider may
share revenue. Networks that maintain a
home shopping or
infomercial format may instead pay the station or cable/satellite provider, in a
brokered carriage deal. This is especially common with
low-power television stations, and in recent years, even more so for stations that used this revenue stream to finance their conversion to digital broadcasts, which in turn provides them with several additional channels to transmit different programming sources.
History Television broadcasting in the United States was heavily influenced by radio. Early individual experimental radio stations in the United States began limited operations in the 1910s. In November 1920,
Westinghouse signed on "the world's first commercially licensed radio station",
KDKA in
Pittsburgh, Pennsylvania. Other companies built early radio stations in Detroit,
Boston, New York City and other areas. Radio stations received permission to transmit through
broadcast licenses obtained through the
Federal Radio Commission (FRC), a government entity that was created in 1926 to regulate the radio industry. With some exceptions, radio stations east of the
Mississippi River received official
call signs beginning with the letter "W"; those west of the Mississippi were assigned calls beginning with a "K". The number of programs that these early stations aired was often limited, in part due to the expense of program creation. The idea of a network system which would distribute programming to many stations simultaneously, saving each station the expense of creating all of their own programs and expandingus transmitted from station to station to listeners across the United States. Other companies, including
CBS and the
Mutual Broadcasting System, soon followed suit, each network signed hundreds of individual stations on as affiliates: stations which agreed to broadcast programs from one of the networks. As radio prospered throughout the 1920s and 1930s, experimental television stations, which broadcast both an audio and a video signal, began sporadic broadcasts. Licenses for these experimental stations were often granted to experienced radio broadcasters, and thus advances in television technology closely followed breakthroughs in radio technology. As interest in television grew, and as early television stations began regular broadcasts, the idea of networking television signals (sending one station's video and audio signal to outlying stations) was born. However, the signal from an electronic television system, containing much more information than a radio signal, required a broadband transmission medium. Transmission by a nationwide series of radio relay towers would be possible but extremely expensive. Researchers at
AT&T subsidiary
Bell Telephone Laboratories patented
coaxial cable in 1929, primarily as a telephone improvement device. Its high capacity (transmitting 240 telephone calls simultaneously) also made it ideal for long-distance television transmission, where it could handle a frequency band of 1 MHz. German television first demonstrated such an application in 1936 by relaying televised telephone calls from
Berlin to
Leipzig, away, by cable. AT&T laid the first
L-carrier coaxial cable between New York City and
Philadelphia, with automatic
signal booster stations every , and in 1937 it experimented with transmitting televised motion pictures over the line. Bell Labs gave demonstrations of the New York–Philadelphia television link in 1940 and 1941. AT&T used the coaxial link to transmit the
Republican National Convention in June 1940 from Philadelphia to New York City, where it was televised to a few hundred receivers over the NBC station W2XBS (which evolved into
WNBC) as well as seen in Schenectady, New York via W2XB (which evolved into
WRGB) via off-air relay from the New York station. NBC had earlier demonstrated an inter-city television broadcast on 1 February 1940, from its station in New York City to another in
Schenectady, New York by
General Electric relay antennas, and began transmitting some programs on an irregular basis to Philadelphia and Schenectady in 1941. Wartime priorities suspended the manufacture of television and radio equipment for civilian use from 1 April 1942 to 1 October 1945, temporarily shutting down expansion of television networking. However, in 1944 a short film, "
Patrolling the Ether", was broadcast simultaneously over three stations as an experiment. feed, allowing the network to broadcast
live television programming to all the stations at the same time. Stations not yet connected received
kinescope recordings via physical delivery. AT&T made its first postwar addition in February 1946, with the completion of a cable between New York City and Washington, D.C., although a blurry demonstration broadcast showed that it would not be in regular use for several months. The
DuMont Television Network, which had begun experimental broadcasts before the war, launched what
Newsweek called "the country's first permanent commercial television network" on 15 August 1946, connecting New York City with Washington. Not to be outdone, NBC launched what it called "the world's first regularly operating television network" on 27 June 1947, serving New York City, Philadelphia, Schenectady and Washington.
Baltimore and Boston were added to the NBC television network in late 1947. DuMont and NBC would be joined by CBS and
ABC in 1948. In the 1940s, the term "chain broadcasting" was used when discussing network broadcasts, as the television stations were linked together in long chains along the
East Coast. But as the television networks expanded westward, the interconnected television stations formed major networks of connected affiliate stations. In January 1949, with the sign-on of DuMont's
WDTV in Pittsburgh, the
Midwest and
East Coast networks were finally connected by coaxial cable (with WDTV airing the best shows from all four networks). By 1951, the four networks stretched from coast to coast, carried on the new
microwave radio relay network of
AT&T Long Lines. Only a few local television stations remained
independent of the networks. Each of the four major television networks originally only broadcast a few hours of programs a week to their affiliate stations, mostly between 8:00 and 11:00 p.m.
Eastern Time, when most viewers were watching television. Most of the programs broadcast by the television stations were still locally produced. As the networks increased the number of programs that they aired, however, officials at the
Federal Communications Commission (FCC) grew concerned that local television might disappear altogether. Eventually, the federal regulator enacted the
Prime Time Access Rule, which restricted the amount of time that the networks could air programs; officials hoped that the rules would foster the development of quality local programs, but in practice, most local stations did not want to bear the burden of producing many of their own programs, and instead chose to purchase programs from independent producers. Sales of television programs to individual local stations are done through a method called "broadcast syndication", and today nearly every television station in the United States obtains syndicated programs in addition to network-produced fare. Late in the 20th century, cross-country microwave radio relays were replaced by fixed-service satellites. Some terrestrial radio relays remained in service for regional connections. After the failure and shutdown of DuMont in 1956, several attempts at new networks were made between the 1950s and the 1970s, with little success. The
Fox Broadcasting Company, founded by the
Rupert Murdoch-owned
News Corporation (now owned by
Fox Corporation), was launched on 9 October 1986 after the company purchased the television assets of
Metromedia; it would eventually ascend to the status of the
fourth major network by 1994. Two other networks launched within a week of one another in January 1995:
The WB Television Network, a joint venture between
Time Warner and the
Tribune Company, and the United Paramount Network (
UPN), formed through a programming alliance between
Chris-Craft Industries and
Paramount Television (whose parent,
Viacom, would later acquire half and later all of the network over the course of its existence). In September 2006,
The CW was launched as a "merger" of The WB and UPN (in actuality, a consolidation of each respective network's higher-rated programs onto one schedule);
MyNetworkTV, a network formed from affiliates of UPN and The WB that did not affiliate with The CW, launched at the same time.
Regulation FCC regulations in the United States restricted the
number of television stations that could be owned by any one network, company or individual. This led to a system where most local television stations were independently owned, but received programming from the network through a
franchising contract, except in a few major cities that had
owned-and-operated stations (O&O) of a network and independent stations. In the early days of television, when there were often only one or two stations broadcasting in a given market, the stations were usually affiliated with multiple networks and were able to choose which programs would air. Eventually, as more stations were licensed, it became common for each station to be exclusively affiliated with only one network and carry all of the "prime-time" programs that the network offered. Local stations occasionally break from regularly scheduled network programming however, especially when a
breaking news or
severe weather situation occurs in the viewing area. Moreover, when stations return to network programming from
commercial breaks, station identifications are displayed in the first few seconds before switching to the network's logo. ==Canada==