Where Four States — and Surveying History — Meet
The Four Corners Monument marks the only location in the United States where four states meet at a single point: Colorado, Utah, Arizona and New Mexico. While millions of visitors know it as the place where you can stand in four states at once, the monument also tells an important story about the history and principles of land surveying in the American West.
The location we recognize today traces back to surveys performed during the nineteenth century, when the boundaries of the western territories were being established across vast and often difficult terrain.
Establishing the Four Corners
In 1875, U.S. General Land Office surveyor Chandler Robbins surveyed the boundary between the Arizona and New Mexico Territories. At its northern end, his survey intersected the boundary previously established between New Mexico and Colorado along the 37th parallel.
Robbins established a monument at that intersection, creating the point that would eventually become the common corner of Arizona, New Mexico, Colorado and Utah as the remaining territorial boundaries were surveyed.
The work was accomplished decades before electronic distance measurement, satellites or GPS. Surveyors relied on astronomical observations, mathematical calculations and conventional surveying instruments while working across remote country.
Is the Four Corners Monument in the Wrong Place?
One of the most interesting stories surrounding Four Corners is the claim that the monument is somehow located in the "wrong" place.
It isn't.
Part of the confusion comes from the coordinate systems used when the original boundaries were established. The Arizona–New Mexico boundary was defined by Congress as the 32nd meridian west of the Washington Meridian, rather than by longitude measured from the Greenwich Meridian used today. Robbins understood this distinction and discussed it himself shortly after completing his survey.
Modern geodetic calculations indicate that the physical monument may differ by roughly 1,800 feet or less from a theoretical reconstruction of its originally intended coordinate. That does not mean the state boundary is somewhere else. The National Geodetic Survey specifically notes that the Four Corners Monument correctly marks the intersection of the four states.
In Surveying, Monuments Matter
Four Corners provides an excellent real-world example of one of the fundamental concepts of boundary surveying.
When a boundary monument is properly established, recognized and accepted, its physical location can become the controlling evidence of the boundary—even when later measurements produce slightly different coordinates.
In other words, the coordinate helps describe the corner; the monument establishes the corner.
That distinction is especially important today. Modern GNSS equipment can determine positions with extraordinary precision, but precision alone does not establish ownership or relocate an existing legal boundary.
The National Geodetic Survey summarized the lesson particularly well when discussing Four Corners: “In surveying, monuments rule!”
From Nineteenth-Century Surveying to Modern GPS
The Four Corners monument has been repaired and replaced several times while preserving the established location. The present monument complex incorporates the familiar survey disk at the intersection of the four states.
Today, the point has also been observed using high-accuracy GPS and is included within the National Spatial Reference System, connecting a boundary established by nineteenth-century surveyors with the geospatial framework used by modern surveyors, engineers and mapping professionals.
More Than a Tourist Attraction
For a land surveyor, Four Corners represents much more than an opportunity to stand in four states at once.
It is a physical connection between historic surveying, congressional boundary descriptions, monumentation, modern geodesy and one of the most important principles of boundary surveying:
A survey is not simply about calculating where a point should be. It is also about identifying, preserving and respecting the evidence that establishes where that point legally exists.
The Four Corners Monument has served that purpose for more than a century—and remains one of the most recognizable survey monuments in the United States.
The Four Corners Associated Monuments
Main Site Monument
Four Corners — A Common Bond
This is the only place in the United States marking the common corner of four states — Colorado, New Mexico, Arizona and Utah.
Who established this corner?
The four corners monument was established and perpetuated by U.S. Government Surveyors and Astronomers beginning in 1868. Surveyors Darling, Robbins, Reeves and Carpenter surveyed the boundary lines between the states.
History of the Monument
In 1899, U.S. Surveyors Hubert Page and James Lentz found the four corners monument disturbed and broken. They marked and set a new stone at the original location. Everett Kimmell, General Land Office, remonumented the Page-Lentz stone with a concrete and brass monument in 1931. The Bureau of Land Management and the Bureau of Indian Affairs poured a concrete paving block around the Kimmell monument in 1962. In 1992, Cadastral Surveyors Darryl Wilson and Jack Eaves officially remonumented the deteriorating Kimmell marker with an aluminum bronze disc. The structure that you see today was rebuilt by the Bureau of Land Management.
Indian Lands
The four corners area is surrounded by Indian Lands. The Navajo Nation lies in New Mexico, Arizona and Utah. The Ute Mountain Ute Nation is located in Colorado. Respect the culture and traditions of the four corners area.
Colorado Monument
Colorado Territory was created in 1861 for its gold, silver and other mineral resources. Its western boundary was designated as 32 degrees of longitude west of the Washington Meridian.
Colorado became a state in 1876. In 1878, U.S. Surveyor Rollin J. Reeves started from the Four Corners Monument and marked a line going north along the boundary of the State of Colorado and the Utah Territory, with a team of surveyors using a 66-foot-long chain and a transit/compass made of wood, glass and brass. The original marked line has been upheld in legal challenges over a more technically precise location.
The Four Corners Monument, first set by Chandler Robbins in 1875, has been replaced and upgraded in 1899, 1931, 1962, 1992 and 2010.
Presented by the
National Society of Professional Surveyors
New Mexico Monument
In 1868 U.S. Surveyor Ehud N. Darling surveyed the 37th parallel of latitude to establish the territorial boundary of Colorado and New Mexico. He placed specially marked stones at intervals along the surveyed line that started at the northeast corner of New Mexico and ended 8702 feet west of what is now the Four Corners Monument.
In 1903, U.S. Surveyor Howard B. Carpenter resurveyed the 37th parallel along a technically more precise location, reporting that the new survey line was located significantly north of the line established by Ehud N. Darling in 1868.
Neither a joint resolution of Congress that was vetoed by President Theodore Roosevelt in 1908, nor a lawsuit filed in 1919 succeeded in relocating the established state line as originally monumented by Darling, which had been accepted, recognized and used by citizens and governments as the official state line.
Presented by the National Society of Professional Surveyors.
Arizona Monument
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 a longitude of 77 degrees 03 minutes, and was the reference 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 triangulated 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.
Presented by the National Society of Professional Surveyors.
Utah Monument
Prior to surveyors setting the Four Corners Monument, this boundless land was inhabited by the Ancestral Puebloans, followed by the Dine, Ute and other indigenous people. Over time, this land was claimed by Spain, taken in war by Mexico, ceded to the U.S. by treaty and organized into territories.
Mormon settlers declared the Provisional State of Deseret in 1849. The congressional Compromise of 1850 created the territories of Utah and New Mexico, separating the free North from the slave South along the 37th parallel of latitude.
U.S. Surveyor Howard B. Carpenter established the territorial line between Arizona and Utah in 1901, running from West to East, ending the survey at the Four Corners Monument. Today, the Four Corners Monument marks the point where the Navajo Nation, the Ute Mountain Ute Reservation, and the States of Arizona, Colorado, New Mexico and Utah meet in peace.
Presented by the
National Society of Professional Surveyors
