Arizona

Arizona. (Four Corners). The line separating the territories of New Mexico and Arizona was established as 32 degrees of longitude west of the Washington Meridian by Congressional Act of February 24, 1863, signed by President Abraham Lincoln., The Washington Meridian bisected the Old Naval Observatory dome at the longitude of 77 degrees 03 minutes, and was the referenced longitude for 11 western states until the Greenwich Meridian was adopted in 1912, conveniently designated as zero degrees longitude., In 1875 U.S. Surveyor Chandler Robbins navigated from the known latitude and longitude of the Ship Rock, surveyed 11.6 miles west to the desired longitude of 109 degrees 03 minutes. Then north to the east-west line previously established by Ehud N. Darling. At that point of intersection, Chandler set a marked stone monument.