 The United States used the Washington Meridian as the longitude reference for most states and territories created between 1861 and 1868.The completion of the first permanent transatlantic telegraph cable on July 28, 1866, allowed the United States Naval Observatory at Washington, D.C. to be synchronized with the Royal Observatory at Greenwich.The need for a separate national meridian for the United States gradually faded, and in 1884, U.S. President Chester A. Arthur called the International Meridian Conference in Washington, D.C. which selected the meridian of the Royal Observatory at Greenwich as the international Prime Meridian.