The 25th meridian of longitude west from Washington is a line of longitude approximately 102.05 degrees west of the Prime Meridian of Greenwich. In the United States of America, the meridian 25 degrees west of the Washington Meridian defines the eastern boundary of the State of Colorado, the western boundary of the State of Kansas, and the western boundary of the State of Nebraska south of the 41st parallel north.
The completion of the first North American telegraph line between Washington and Baltimore on 1844-05-24, introduced a technology that could transmit time signals at the speed of light. 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.