Seattle radio station KIRO began broadcasting as KPCB in 1927. By 1937, the station had become KIRO, and the Federal Communications Commission (FCC) had increased its power from 100 to 1000 watts. Around that time, KIRO became Seattle’s official CBS affiliate. In 1941, with the completion of its new 50,000-watt transmitter on Maury Island, KIRO had become one of the most powerful radio stations in the country. As of 2025, the KIRO station studios are located in the Belltown neighborhood, with a transmitting tower adjacent to the station’s original studios on Queen Anne Hill.

The first panel of this poster celebrates KIRO’s transition to 50,000 watts. The second panel shows a map of the station’s coverage in Washington, Oregon, California, Idaho and Montana. The third panel shows the variety of advertising options that KIRO used to promote its new, increased coverage.