In the 30's of the twentieth century, Western Union has become the world's largest telegraph company. Another invention of Western Union - time synchronization. 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. July 3, 1884 the company's shares were included in the calculation base for the newly created stock index Dow Jones Transportation Average. Western Union made so that the time in all of American civil services was the same. 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.