ABC 4 presented the first television demonstration in the intermountain area at the Paris Department Store in Salt Lake City in 1939. NBC had sold radio owner, Sid Fox, a television demonstration unit that consisted of one camera, a control unit, six receivers, and a small closed circuit transmitter. In September of that year, the unit was installed and public demonstrations were given for three weeks.
The unit was also set up at the Utah State Fair for the next two years. There were speeches by LDS President Heber J. Grant, Governor Henry H. Blood, Salt Lake City Mayor John M. Wallace and a fashion show with music by Woodbury Orchestra.
The federal government recognized ABC 4 as an official pioneer experimental station with the call letters W6XIS. This allowed the station to use homemade TV cameras, erect an antenna tower which became famous as the Walker Bank Tower, and to broadcast test patterns and music.
Intermountain Broadcasting Corporation in Salt Lake City, Utah operated radio station KDYL, which applied for an experimental television broadcasting license from the FCC in 1945, using a demonstration kit acquired from RCA in 1939.
ABC 4 officially signed on the air April 19, 1948 as KDYL-TV. This milestone established Utah as the first state between St. Louis and the West Coast to have a television station. KDYL was the first privately owned television station in the United States (the other twelve were owned by manufacturers, newspapers, experimental laboratories, and the motion picture industry).
By 1952, the station was serving its audience with more than 100 hours of programming, 9:30 a.m. to midnight, seven days a week. The station had one of the longest schedules in the nation.
ABC 4 originated America's first national, live views of the state's famous ski slopes (downhill ski racing from Alta, Utah), televised the first nationally viewed golf match, showed cultural offerings such as the Virginia Tanner Dancers to the country in the early 1950s, presented early national broadcasts of the Mormon Tabernacle Choir, and televised the Pioneer Days Parade for the first time ever.
ABC 4 had many "firsts" over the years. In 1953 and '54 Dr. Robert Warner of Salt Lake City initiated the nation's first series of open-circuit continuing medical education clinics via KDYL-TV. In 1999, ABC 4 was the first television in Utah to "flip the switch" and broadcast a digital signal. On June 12, 2009, KTVX ceased analog broadcast.
On April 26, 2010, KTVX began broadcasting news in full high definition. The station also unveiled a brand new set on that date.
On July 19, 2012, an agreement was reached for Nexstar Broadcasting Group to purchase KTVX. Nexstar officially took ownership of ABC 4 and CW 30 on December 3, 2012.