According to the Congressional definition of the boundary of Colorado, this point is theoretically where the 40th parallel north latitude intersects 25 degrees west longitude as measured from the Washington Meridian*.  However, this monument was first set by Oliver Chaffee during his 1869 survey -- and due to the technological limitations of his day, it is not exactly right (although his survey does define the official boundary, regardless of its accuracy).

* 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.  "25 degrees west of Washington" is a few miles away from the 102nd degree of longitude west of Greenwich.

Note: The book "Colorado Mapology" (Erl H. Ellis, 1983, Jende-Hagan Book Corporation) is an excellent resource, from which I obtained much of the information presented on these pages. 

This photo was looking southeast; visible in the foreground is the original limestone marker:

Ellis, 1969

​Here are some closeups, showing what was left of the inscriptions "25° W" and "40° N":

Ellis, 1969 (looking north)

Ellis, 1969 (looking west)

Since then some attention has been given to the site.  This monument has been replaced (presumably in the 1970s or 1980s); perhaps it was during the same occasion that the area was enclosed with a fence and spruced up to the degree shown in the following photos.  This corner was a little hard to find -- the roads were not all that great.  This sign was helpful, though:

Sanderson, fall 1993

The view here was mostly south, and a little east (roughly the same as the first 1969 photo above -- note the tree in the background).  I was standing in the northwest corner of Kansas.  The camera was in Colorado; the line of fence posts running diagonally across the photo are on Colorado's east line.  Nebraska is just left (east) of the camera.  In the distance the breaks of the Arikaree River are visible (the point where that stream flows out of Colorado is the lowest elevation in the state):

Sanderson, fall 1993

I wonder where the old limestone monument is now?  Too bad it's gone -- it has been replaced with a USGS benchmark set in concrete.  There was also a mailbox for the visitor register, with a quaint little painting which illustrated each state bird and state flower:

Sanderson, fall 1993

That photo was looking northeast into Nebraska; here is a close-up of the benchmark:

Smith, Feb. 2009

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Research and/or photo credits: Dale Sanderson; Scott Smith

Page originally created 1998;
last updated Nov. 17, 2016.