"The first transcontinental Morse telegraph wire put up in 1861 between Omaha and Sacramento eventually only had automatic repeaters at Fort Laramie in eastern Wyoming, Salt Lake City Utah, and Virginia City, Nevada which replaced manual relaying at those stations."
As an interesting aside – it was this event that killed the much glamorized and short lived (about 18 months) Pony Express. Although it is often thought that the transcontinental railroad killed the Pony Express – it actually died 6 or 7 years before the 1869 railroad completion.
Tom Peterman