Leaving the idea of expansion into Europe, Western Union took up the expansion of services in the U.S. market. In 1877, starting from September, New York City residents began to have the opportunity to check the time on clock with the "time ball", located on the roof of constructed in the same year a new corporate headquarters - Western Union Building. In the early 60s Western Union has put into operation transcontinental microwave system of data transmission via radio waves, completely replacing the web of telegraph poles and wires. Thanks to cooperation with Western Union the Associated Press at the end of the XIX century took almost monopolistic position in the U.S. market news. In 1884 Western Union has become a joint-stock company and was brought to the stock exchange. The company has entered in the first American stock index Dow Jones. Sibley, the founder of Western Union, did not build a new telegraph lines, and persuaded the other players to join. American Telegraph Company, however, still had to buy it.