Telephone Northwest on February 1, 1960, then filing articles of incorporation for Pacific Northwest Bell, the new entity that would serve the region, on March 27, 1961. The Washington Public Service Commission approved the formation of Pacific Northwest Bell on June 5, with the separation occurring at midnight on July 1. Its service territory included Oregon, Washington and northern Idaho (Southern Idaho was served by Mountain Bell). The new company's first major job was to build the world's most advanced telephone service to serve the Seattle World's Fair which was scheduled to open in less than ten months (April 21, 1962.) This was accomplished. AT&T breakup On January 1, 1984, as part of the breakup of AT&T, Pacific Northwest Bell, Mountain Bell and Northwestern Bell became part of US WEST. The company continued to use the logo it adopted in 1969 but also used a variation which included the tagline "A USWEST Company". In 1988, all three of US WEST's operating companies began doing business as US WEST Communications. However, the three companies remained legally separate until January 1, 1991, when US West merged its operating companies into Mountain Bell. On the same day, Mountain Bell changed its name to US WEST Communications. The Pacific Northwest region went from having been a part of Pacific Bell before 1961 to becoming a part of Mountain Bell. The name is still a registered federal trademark and the domain pacificnorthwestbell.com is also active and points to the website CenturyLink. Prior to 1984, AT&T held 89.3% in Pacific Northwest Bell. Headquarters Pacific Northwest Bell's headquarters was located in a 32-story building at 1600 Seventh Avenue in Seattle. The building, which was constructed in 1976, was retained by US West and Qwest; CenturyLink sold it in 2012 after acquiring Qwest the previous year. References Bell System Lumen Technologies Economy of the Northwestern United States Telecommunications companies disestablished in 1991 Defunct telecommunications companies of the United States Telecommunications companies established in 1961 American companies established in 1961 Communications in Washington (state) Communications in Idaho American companies disestablished in 1991