The Washington Meridian

or, the American Meridian

During a relatively brief period beginning in 1850, the "prime meridian" in the United States was not "the Prime Meridian" (i.e. the Greenwich Meridian), but rather the "American Meridian" (also known as the "Washington Meridian").  This meridian was defined as passing through the center of the original dome atop the main building of the Naval Observatory in Washington, DC (the old Naval Observatory, that is, not the current one).  Despite the fact that the U.S. used this meridian for only a few decades, it was during this timeframe that the boundaries of several western states were established.  Included among these were both the eastern border of Colorado, my home state (defined as 25 degrees west of Washington), and the west boundary (32 degrees west of Washington).

It's interesting to note that there were actually a total of four "prime meridians" used by the U.S. prior to its 1912 adoption of the Greenwich Meridian.  The original American Meridian passed through "the Congress House" (today's Capitol building).  A later meridian was defined as passing through "the President's House", now known as the White House.  (Several other features are also located on this meridian, the most conspicuous of which are the Jefferson Memorial and 16th Street NW.)  The third American Meridian was through the old Naval Observatory, as described above (24th Street NW lies along this meridian).  The Naval Observatory moved to its present location on Massachusetts Avenue in 1893, prompting the fourth meridian, which passed through the clock room: a small building located at the center of the 1000-foot radius of the observatory grounds.  After the Naval Observatory was moved, the original facility has housed various other Naval departments*.  Currently the "Observatory Hill" complex (as it is sometimes referred to nowadays) is home to the Navy Bureau of Medicine and Surgery (or Bu-Med for short).

Of these four American Meridians, it appears that only the third (the one through the old Naval Observatory) was ever used in defining any state boundaries.  Over the years I have made some effort to visit each of Colorado's corners, and along the way I have gleaned a bit about how the state's boundaries were defined and surveyed.  So as I was preparing for a summer 2009 family trip to Washington, DC, one of the places I was interested in visiting was the old Naval Observatory, since the boundaries of my state are defined in relation to this building.  However, I soon learned that Bu-Med is unfortunately not open to the public**.  Too bad... but I did receive something of a consolation prize: as my family was walking from the Arlington Cemetery to the Lincoln Memorial, I caught sight of a small white observatory dome off to the north.  Conscious of what I was looking at, I took this photo...



...and then, right there on the Arlington Bridge, I proceeded to give my family a brief lecture on the relationship of that building to the shape of our own state, hundreds of miles off beyond the western horizon.  (Alas, it was received with rolling eyeballs and much less interest than I would've hoped.)  Later on that same trip, we visited the American Meridian plaque, at the southeast corner of 24th and "H" streets:



I have a few problems with the text of that plaque, foremost of which is the fact that all of the specified lines of longitude appear to be off by two degrees! Wyoming's east and west lines are actually 27 and 34 degrees, respectively; while Colorado's are 25 and 32 degrees. And I'm not sure Oregon's eastern border was really defined according to this meridian. In fact, I don't think any of California's or Washington's borders have anything to do with this meridian, either.

On the sidewalk at the foot of that marker, a granite strip is inlaid among the bricks, engraved with the text "The American Meridian":

The design of this small monument can lead you to believe that you're standing right on the actual meridian, but from what I observe on aerial photos, I'm skeptical that's truly the case.  Rather, it appears 24th St sits on the actual meridian.  (Or, probably more accurately, the observatory was built upon the centerline of 24th Street's right-of-way, and thus 24th became the de facto meridian).  Of course it wouldn't have been practical to put a marker in the middle of the street, so I imagine this site along the sidewalk was deemed to be close enough. But it's given rise to some dubious claims. For example, it's been stated that this Meridian bisects some of the buildings on the George Washington University campus. Well, 24th Street doesn't run through any buildings, so I don't think the Meridian does, either. I suspect these misconceptions can be traced back to the placement and design of this monument, and the way things are worded on the plaque.

Anyone who's had elementary-level geography should be familiar with the concept of the Prime Meridian, but it would seem far fewer people are aware of the fact that the U.S. once had a different "prime meridian" of its own.  As we've seen, the position of this meridian was determined by the location of an observatory. Or, to put it another way, the meridian was not defined in relation to a whole-integer degree of longitude west of Greenwich. The American Meridian was about three arc-minutes away from 77 degrees west of Greenwich - this translates to nearly three miles. Chandler Robbins, the man who led the survey team that set the original Four Corners monument, anticipated the confusion that this offset might cause. In a letter to the Santa Fe newspaper, he wrote the following about the west boundary of Colorado:

"It seems to have been the general impression that the line was the 109 degrees of longitude west of Greenwich. Such is not the case, as the law makes it 32 degrees of longitude west from Washington, which corresponds to 109 degrees 02 minutes 59.25 seconds west from Greenwich, and which places the line a small fraction less than three miles farther west than would have been the case if it had been run as the 109 degrees of longitude."

This letter was written way back in 1875. We've had plenty of time to absorb the facts. But every now and then someone notices that the Colorado/Utah stateline isn't exactly on the 109th Meridian west of Greenwich.  Sometimes someone in the news media latches on to this fact, and sometimes they fail to fully research the issue before announcing to their audience something along the lines of "The Four Corners Monument is off by 2.5 miles!" Claims like this are patently untrue. For one thing, the location of Four Corners (and several other state boundaries) was not defined in terms of the Greenwich Meridian - it was never intended to be located at 109 degrees west of Greenwich. Secondly, even if a boundary monument is not located exactly where it ought to have been (which is true in just about every case, to a greater or lesser extent), once the boundary as surveyed has been accepted by the relevant jurisdictions, that becomes the legal boundary... regardless of any future claims of inaccuracy.

Footnotes, references, and links

*A concise history of the grounds of the old observatory is given here:
http://www.nlm.nih.gov/hmd/medtour/bumed.html

**Bu-Med was not closed to the public back in 1972, when a gentleman by the name of Lenny Abbey wanted to visit the observatory (although for a different reason than mine).  I'm grateful that he has posted his recollection on the web...
http://www.labbey.com/Telescopes/Washington.html
... not only because it's interesting to note how the usage of these buildings has changed over the years, but also because it helped me to determine that it was the original (smaller) dome that was in use when western states were being defined, not the second (larger) dome, which has since been replaced with a more conical roof.  It was with a telescope under this larger dome in 1877 that Asaph Hall discovered the natural satellites of Mars.  But that telescope wasn't built until 1875, so I think it's pretty safe to assume that during the 1860s (when Congress was defining the boundaries of twelve western states and territories), only the one smaller dome was extant at the old Naval Observatory.  This is a well-written and fascinating page, and I highly recommend it.

I also used these pages as sources:

http://www.ngs.noaa.gov/INFO/fourcorners.shtml
http://www.howderfamily.com/blog/?p=2373
http://en.wikipedia.org/wiki/Washington_meridian
http://encyclopedia.gwu.edu/gwencyclopedia/index.php?title=American_Meridian