that the carbons of Yost's letters contain no letterheads. Things became less confusing when the Tri-State and Dakota Central companies were folded into the Northwestern Telephone Exchange Company. In 1909, a single general office staff for the Iowa, Nebraska and Exchange companies was established in Omaha. On December 10, 1920, Iowa Telephone changed its name to Northwestern Bell Telephone Company. In January, 1921, the Nebraska and Northwestern Telephone Exchange companies were merged into the new company. While the new company was incorporated in Iowa, its headquarters remained in Omaha. Sale of telephone lines In 1976, Northwestern Bell sold access lines in the Midland, Philip, Martin, White River, Milesville, and Hayes exchanges to Golden West Telephone, a small telephone cooperative in South Dakota. Headquarters The Northwestern Bell headquarters, now the AT&T Building (owned by CenturyLink), was located at 118 South 19th Street in Omaha, Nebraska. Name usage The Northwestern Bell name is still licensed for use today on telephone equipment produced by Unical Enterprises; otherwise, the NWBT name has disappeared. Dex Media white pages lists a customer service number under the Northwestern Bell name (which connects to Qwest). Additionally, the NorthWesternBell.com domain is still active and rolls over to the CenturyLink webpage. References Bell System Lumen Technologies Economy of the Midwestern United States Defunct telecommunications companies of the United States American companies established in 1896 Telecommunications companies established in 1896 Communications in Nebraska Communications in Iowa Communications in Minnesota Communications in South Dakota Communications in North Dakota American companies disestablished in 1991 Telecommunications companies disestablished in 1991