The first transcontinental telegraph (completed in 1861) was a line that connected an existing network in the eastern United States to a small network in California by a link between Omaha and Carson City via Salt Lake City. It was a milestone in electrical engineering and in the formation of the United States of America. It served as the only method of near-instantaneous communication between the east and west coasts during the 1860s.
After the development of efficient telegraph systems in the 1830s, their use saw almost explosive growth in the 1840s. Samuel Morse‘s first experimental line between Washington, D.C. and Baltimore – the Baltimore-Washington telegraph line – was demonstrated on May 24, 1844. By 1850 there were lines covering most of the eastern states, and a separate network of lines was soon constructed in the booming economy of California.
The federal contract authorized through the Pacific Telegraph Act of 1860 was awarded to Hiram Sibley, the president of the Western Union Company. He then formed a consortium between Western Union and the telegraph companies in California: to share the efforts of constructing the overland telegraph, to split up the federal and state subsidies, and to share any profits from operation of the line. The newly consolidated Overland Telegraph Company of California would build the line eastward from Carson City (the eastern terminus of their lines), using the newly developed central route though Nevada and Utah. At the same time, the Pacific Telegraph Company of Nebraska was formed by Sibley. It would construct a line westward from Omaha, essentially using the eastern portion of the Oregon Trail. The lines would meet at a station in Salt Lake City.
Materials for the line were collected in late 1860, and construction proceeded during the second half of 1861. Major problems in provisioning the construction teams were overcome, and there was a constant shortage of sources of telegraph poles on the plains of the Midwest and the deserts of the Great Basin. The line from Omaha reached Salt Lake City on October 18, 1861, and the line from Carson City was completed on October 24.
The telegraph line immediately made the Pony Express obsolete, and it officially ceased operations two days later. The overland telegraph line was operated until 1869, when it was replaced by a multi-line telegraph that had been constructed alongside the route of the Transcontinental Railroad.