Harriman was nearly 50 years old when in 1897 he became a director of the Union Pacific Railroad. By May 1898, he was chairman of the executive committee, and from that time until his death, his word was the law on the Union Pacific system. In 1903, he assumed the office of president of the company. From 1901 to 1909, Harriman was also the president of the Southern Pacific Railroad. The vision of a unified UP/SP railroad was planted with Harriman. (The UP and SP were reunited on September 11, 1996, a month after the Surface Transportation Board approved their merger.)