The first transcontinental telegraph line across the United States is completed.

The first transcontinental telegraph (completed October 24, 1861) was a line that connected the existing telegraph network in the eastern United States to a small network in California, by means of a link between Omaha, Nebraska and Carson City, Nevada, 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. For comparison, in 1841, it had taken 110 days for the news of the death of President William Henry Harrison to reach Los Angeles.