Two years later on 1863-02-24, the Act Organizing the Territory of Arizona defined the eastern boundary of the new territory as the 32nd meridian of longitude west from Washington. This in turn moved the western boundary of the Territory of New Mexico east to this meridian.
These boundaries on the 32nd meridian of longitude west from Washington remained when Colorado became a state on 1876-08-01, Utah became a state on 1896-01-04, New Mexico became a state on 1912-01-06, and Arizona became a state on 1912-02-14. The point of intersection of these four states, known as the Four Corners, is the only place in the United States where four states touch.
The completion of the first North American electrical telegraph line between Washington and Baltimore on 1844-05-24, introduced a technology that could transmit time signals nearly instantly. On 1850-09-28, the United States adopted two primary meridians of longitude for officially use: the Greenwich Meridian (through the old Royal Observatory at Greenwich, England) for all nautical and international use, and the Washington Meridian (through the old United States Naval Observatory in Washington, D.C.) for more accurate astronomical and domestic use. The completion of the first telegraph line across North America on 1861-10-24, allowed time signals from the Naval Observatory in Washington to be transmitted across the continent.
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 1866-07-28, allowed the Naval Observatory at Washington 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 which selected the meridian of the Royal Observatory at Greenwich as the international Prime Meridian. On 1912-08-12, the United States adopted the Prime Meridian of Greenwich for all uses domestic and international.