AT&T President Theodore Vail made a transcontinental telephone line in a 1908 statement. The company had begun building the nation’s original long-distance network in 1885, starting from New York. The service had reached Chicago by 1892, but signal weakness over distance was proving to be a major issue. In 1909, the AT&T chief engineer predicted that AT&T would open a transcontinental line in time for San Francisco’s 1915 exposition marking completion of the Panama Canal. Dr. Lee de Forest’s invention of the audion—a three-element vacuum tube—led to AT&T’s success. The company purchased patent rights from de Forest and developed high-vacuum tubes—to be used as signal amplifiers—by mid-1913. The transcontinental line was completed on June 27, 1914.