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100 years of US routes: 1926-2026
(referred to as Corner G on this page)
According to the Congressional definition of the boundary of Colorado, this point is theoretically where the 37th parallel north latitude intersects 103 degrees west longitude*. The first three attempts to locate this intersection (1857, 1859, and 1881) were later found to be in error. The fourth (and finally accepted) location was set in 1900 by Levi Preston. However, due to the technological limitations of his day, it is not exactly right either (but it is remarkably close, and at any rate, his survey does define the official boundary, regardless of its accuracy). This was originally a sandstone monument, but during his 1928 resurvey Arthur Kidder replaced it with the current granite marker shown below.
* Many American surveys between 1850-1884 were based on the Washington Meridian, which was officially abolished by Congress in favor of the Greenwich Prime Meridian in 1912. This point is one of the few Colorado corners that was defined as a degree of longitude west of Greenwich (as opposed to "west of Washington").
In 1857 the south line of Kansas Territory was surveyed along the 37th Parallel by J.E. Wyess (as a part of the Johnston expedition). The intended endpoint was at the 103rd Meridian, where the line intersected New Mexico Territory. The monument placed by this expedition came to be known as the Johnston Monument. Modern topographical maps show that the Johnston Monument was almost exactly on the 37th Parallel, but due to an error on the part of the astronomers, it was nearly 4.5 miles west of the 103rd Meridian.
In 1859, officials in DC determined that the Johnston Monument was in the wrong location, so they supplied the correct calculation to Capt. John N. Macomb, who established a new monument at what he determined to be the correct location. Modern topos show that this monument was almost exactly on the 37th parallel. However, it was later found that the Macomb Monument was also incorrectly located, this time about 2.5 miles west of the 103rd Meridian.
In 1881 the first accepted location for this corner was established when Richard O. Chaney and William W. Smith surveyed the 103rd Meridian as the boundary between present-day Oklahoma and New Mexico. However, they did not correctly identify the 37th parallel, and as a result the Chaney-Smith Monument was positioned about a quarter-mile too far north.
In 1900 Levi S. Preston was tasked with re-surveying the north boundary of New Mexico between the Macomb Monument and the Cimarron Meridian (i.e. the 103rd Meridian). As a part of that survey he established the fourth (and final) location of this tri-state corner. Modern topos show that the Preston monument is about .17 mile due south of the Chaney-Smith Monument. It is almost exactly on the 37th parallel, and a small fraction of a mile west of the 103rd Meridian.
In 1928 Arthur Kidder began his work on another survey of the Colorado-New Mexico border. He found the Macomb Monument and reconstructed it. He also found the Cheney-Smith Monument, as well as the Preston Monument, which he rebuilt, and that version is the one that still exists today.
The view in this photo was to the west. I was standing in the northeast corner of New Mexico; my father (on the right) was standing in Colorado. The fenceline behind his hat runs along the Colorado-New Mexico line. The northwest corner of Oklahoma's panhandle is just to the left (south) of the camera, and directly in front of me. The state names are inscribed on the marker:
Sanderson, fall 1993
Research and/or photo credits: Dale Sanderson
Page originally created 1998;last updated Feb. 1, 2026.
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