The station was founded as KTNT-FM and was owned by The Tacoma News Tribune. It signed on the air on October 26, 1948. The station was powered at 10,000 watts, a fraction of its current output, and exclusively targeted Tacoma and South Puget Sound. The Tacoma News Tribune added an AM station in 1952, KTNT ; and in 1953, KTNT-TV. The callsigns for the three stations stood for Tacoma News Tribune.
KNBQ
In 1976, the call letters were changed to KNBQ. While the AM station carried a personality adult top 40 sound, the FM station switched to an automated music-intensive Top 40 format branded simply as "97.3 KNBQ." In the 1980s, the Tacoma News Tribune boosted KNBQ's power to 100,000 watts. The Federal Communications Commission granted a construction permit to increase the antenna height to 1,480 feet, moving the transmitter to Tiger Mountain. That greatly increased the station's value, now able to compete in the entire Seattle-Tacoma media market. In 1987, KNBQ was sold to the original iteration of Viacom. Viacom kept the Top 40 format but used a "no talking over the music" policy to differentiate KNBQ from other Seattle Top 40 outlets.
KBSG
On February 1, 1988, the station flipped to an oldies format as "K-Best 97.3." It picked up the KBSG-FM call letters. K-Best concentrated on the biggest hits of the 1960s, with some 1970s songs with a few late 1950s hits. As the station moved into the 1990s, the 70s titles were increased and the 50s songs were removed. Entercom bought the station in 1996. For many years, KBSG-FM was simulcast on co-owned AM 1210 KBSG in Auburn. This lasted until 2002, when AM 1210 was sold to Bustos Media, which specialized in Spanish language formats. On August 1, 2007, after Entercom traded KBSG, KIRO and KTTH to Bonneville as part of a multi-market station swap. KBSG was rebranded from "KBSG 97.3" to "The New B97.3," and dropped the word "oldies" from the station's title. The station's playlist was moved to more 1970s and 80s music, with fewer 60s titles. The format moved from Oldies to Classic Hits. Exactly one year later, on August 1, 2008, the station's call letters were switched to KIRO-FM.
KIRO (AM) to KIRO-FM transition
On August 12, 2008 at 4:23 a.m., the 97.3 frequency began to simulcast co-owned news/talk radio station AM 710 KIRO. The final song on 97.3 as a classic hits station, Start Me Up by the Rolling Stones, faded out as the FM station joined KIRO AM's Wall Street Journal This Morning in progress. On April 1, 2009, KIRO-FM became the primary station as the simulcasting on KIRO came to an end. It marked the completion of the station's transition to the FM frequency that began in August 2008. KIRO is now a sports talk station, branded as "710 ESPN Seattle." Also moved from KIRO 710 to KIRO Radio 97.3 FM were the NFL broadcasts of the Seattle Seahawks Radio Network. KIRO-FM is now the flagship station for the team's play-by-play and the pre- and post-game shows. The Seahawks have been heard on KIRO AM 710 in Seattle since the NFL franchise was launched in 1976.
