KDLH began broadcasting on March 14, 1954, as KDAL-TV and aired an
analog signal on
VHF channel 3. It took its calls from the initials of its founder, Dalton Alexander LeMasurier, who owned the station along with
KDAL radio (610 AM). It switched affiliations with WDSM-TV (now KBJR) in 1955 and joined CBS. It also aired some
ABC programs in off-hours, splitting them with WDSM-TV, until
WDIO-TV signed-on in 1966. The station's original studio facilities were located with KDAL Radio in the Bradley Building (demolished) moved to West Superior Street in downtown Duluth in the mid-1960s. During the late-1950s, KDAL was also briefly affiliated with the
NTA Film Network. The LeMasurier family sold KDAL-AM-TV to what eventually became
Tribune Broadcasting in 1960. KDAL began broadcasting in color in 1965. In 1979, Tribune sold the station to Palmer Broadcasting, who changed the call letters to the current KDLH-TV on February 16. Palmer Broadcasting then sold KDLH to
Benedek Broadcasting in 1985. The station dropped the "-TV" suffix in 1991. Benedek went
bankrupt in 2002, and most of the company merged with
Gray Television in 2001. However, KDLH was not included in the merger and was sold to Chelsey Broadcasting instead.
New Vision Television bought the station in 2003. In March 2005, the Malara Broadcast Group purchased channel 3 from New Vision and outsourced most of the station's operations to longtime rival KBJR, who was owned by
Granite Broadcasting. Under this agreement, KDLH laid off most of its staff. Filings with the
Federal Communications Commission (FCC) showed Malara could operate KDLH with as few as two people on the payroll. KDLH's digital transmitter had been operating at reduced power with a substitute side-mounted antenna after a May 18, 2008, fire that severely damaged its main digital antenna. It returned to full power on UHF channel 33 by June of that year. In February 2009, Malara Broadcasting announced that KDLH would not make the switch to all digital later in the month due to the fire. With that announcement, the station was the only one in the area still broadcasting in analog after February 19 as KBJR,
WDSE, WDIO, and
KQDS-TV all went digital-only on that date. On June 12 at around 7 p.m., KDLH ceased normal broadcasting operations on its analog signal. At that time, the analog station began a
nightlight signal consisting of a ten-minute digital television informational video on a constant loop. On June 26, two weeks after regular broadcasts had ended, the nightlight signal was terminated with the help of Bob Peterson (a former engineer at the station who helped launch KDLH in 1954) bringing an end to all full-power analog broadcasting in the area. In November 2009, the station re-branded from "CBS 3" to "KDLH 3". This brought a new logo to the station for the first time since it merged with KBJR. On February 11, 2014, it was announced that
Quincy Newspapers would acquire KBJR-TV and KRII from Granite Broadcasting. Malara initially planned to concurrently sell KDLH to
SagamoreHill Broadcasting; however, that November, the deal was reworked to remove SagamoreHill from the transaction, and as a result KDLH would remain with Malara. Quincy would continue to provide services to KDLH. The sale was completed on November 2. The move ended KDLH's 61-year association with the CBS network. On May 21, 2018, it was announced that Quincy Media would acquire KDLH outright for $792,557. While the FCC normally prohibits one company from owning two television licenses in the same market when both are among the top four rated stations, Quincy submitted a filing saying that during the November 2017 "sweeps" period, KBJR-TV was the top ranked station while KDLH placed fifth. The sale was completed on August 1. On February 1, 2021,
Gray Television announced its intent to purchase Quincy Media for $925 million. The acquisition was completed on August 2, making KBJR and KDLH
sisters to Gray stations in nearby markets, including CBS/Fox affiliates
KEYC-TV in
Mankato and
WSAW-TV/
WZAW-LD in
Wausau, and NBC affiliates
WLUC-TV in
Marquette and
WEAU in
Eau Claire, while separating from their former Wisconsin sister stations which were divested in order to complete the purchase. ==News operation==