Location: Denver, CO
Started: 1911
Sold to/Ended: Merged with Colorado Telephone Co and Rocky Mountain Bell to form Mountain Bell, 1911

History: Tri-State was a relatively large company. It was a fully owned subsidiary of the Colorado Telephone Co. formed to operate exchanges in New Mexico, Arizona and Texas and to bypass regulation by the Colorado Public Utilities Commission. It was a company on paper, but when AT&T mandated the company be merged with Colorado Telephone and Rocky Mountain Bell to form Mountain States Tel. & Tel. (technically, the new Mountain States Co. purchased Rocky Mountain Bell), Tri-State stock was issued to a group of Colorado Telephone Co. executives. Actually, the Tri-State company continued (on paper) until 1919.