In the early forties of the 20th century, Western Union has used the first time a commercial intercity microwave transmission system. In the 30's of the twentieth century, Western Union has become the world's largest telegraph company. In 1866, Sibley ordered the engineers to develop a Western Union telegraph system of stock quotes in real time. July 3, 1884 the company's shares were included in the calculation base for the newly created stock index Dow Jones Transportation Average.