It’s All in the Meridian - an Overview of Meridian Lines

By Gaby M. Neunzert, PLS
One of the more noticeable visual effects of a United States and Canada political map are some of the “straight line” boundaries of the western states or provinces. Usually boundaries follow natural features such as rivers, shore lines or watersheds, but, for example, Colorado and Wyoming are bound by east-west and north-south lines artificially drawn on a white paper and physically anchored in a featureless landscape. Both states would show up as rectangles on a Mercator map, even though on the ground the north-south boundaries as meridians converge on the North Pole and the east-west lines are parallel, small circle routes. Most of these states or provinces were created on paper during the 1840-1870 time period, with their boundaries physically surveyed on the ground some time later. Drawing these boundaries on a map, especially on a Mercator projection, is very easy, i.e., draw a rectangle; surveying the same boundaries on the ground before GPS and portable time, was considerably more difficult. With a transit and without calculations, establishing true north for the meridian involved mechanically splitting sightings of Polaris or a circumpolar star at eastern and western elongation. But since flashlights had not been invented, a lantern with a candle had to be used to illuminate the cross hairs and make field notes. At lower latitudes sighting Polaris was easy since the star was only 35º to 40º above the horizon and prolonging a straight line towards it produced good results; weather and a remote location aside, running the border between Alaska and Canada could not have been easy with the pole star further and further overhead.

Compared to physically running a meridian, establishing a predetermined longitude to any degree of accuracy was almost impossible. Since the determination of longitude involves time, a portable chronometer, sufficiently rugged to survive the “wild west” and good ephemeris tables were needed. An error of one second in time produced an error of very roughly 1200 ft. on the ground. Sighting stars with a 1-minute transit and poorly illuminated spider web cross hairs, probably yielded location accuracies of several minutes of arc or very roughly a mile. Getting a meridian initially located even near its intended position and later locating that same meridian further north or south to continue the line, speaks very highly of the original surveyors and their skills. Thus considering for example the 72nd meridian, which runs from the U.S.-Mexican border, through the Four Corners area to the southern border of Wyoming and is, including a slight dogleg on Colorado’s western boundary, about 743 miles long.
In addition to controlling Canada’s provincial boundaries, meridians also are used to define the Principal Points of the Dominion Land Survey; conceptually similar to the U.S. Land Survey System. Starting with the First Meridian (97º27’28.41”W) and then the Second through Seventh Meridian (102º, 106º, 110º, 114º, 118º, and 122ºW), Principal Points are located at about 24 mile intervals north or south, at the intersection of the respective Meridian and an east-west small circle route called “Base Line.” Many Canadian Sections, just like in the U.S. about 1 mile X 1 mile, are surrounded on the outside by a “road allowance” either 1.5 chains or 1 chain wide. A word of caution: in a Township, Canadian Sections are numbered differently than American Sections!
Given the nature of cartographers, surveyors and maybe even politicians, laying out a meridian at random values, unless dictated by topography, is not “neat.” Seven boundary meridians (25º, 27º, 32º, 34º, 37º, 39º, and 40º) were laid out as integer values west of Washington, DC and yet another four (100º, 103º, 120º, and 141º) were reckoned from Greenwich. Washington, or more specifically the old Naval Observatory, was the official reference for the prime U.S. meridian from September 28, 1850 until August 22, 1912 for astronomical observations only, i.e. mapping on land, etc. During all this time Greenwich was used for navigation and it possibly would be of some interest to see how a harbor map of this time period referenced land by one meridian and water by another meridian. As chair of the International Geographic (or Meridian) Conference in 1884, the U.S. led the affirmative drive to make Greenwich the internationally accepted 0º or prime meridian through the Royal Greenwich Observatory on the outskirts of London. Without additional research, it appears that by Congressional action the Washington meridian was rescinded in 1912, but the Greenwich meridian has been adopted since 1884 by consensual usage only – just like the metric system – since April 5, 1893.
The 141st meridian as the boundary between Alaska and Canada is worth dwelling on a little longer. Alaska, or “Seward’s Folly”, was purchased from Russia in 1867 for $7,200,000 in gold Included in the purchase was an 1825 boundary treaty between Russia and Great Britain for the 141st meridian boundary, which the U.S. accepted without anybody ever seeing any physical evidence. It was not until1913 that the survey was finally completed and intervisible monuments were set and a 20 ft. wide right-of-way (also called a vista) was clear cut for most of its 647 mile length. Monument #1 is on the shore, near the hamlet of Gordon and Demarcation Point on the Beaufort Sea, the last monument, #181, was set on the south bank of the White River at elevation 3549 ft. From there the meridian line steadily climbs and probably is unmarked by monuments, mostly above the timber line and over glaciers, for about 98 miles to the southern terminus. According to modern maps, this point is on a glacier at roughly 12,800 ft. elevation and is located about 2.6 miles to the NW of Mt. Saint Elias, the “official” southern end referred to by Van Zandt. At a salary of only a few dollars a day, some very thorough surveyors probably reflected on (or maybe cursed) “Seward’s Folly” considering that there were no human settlements within hundreds of miles, no snowmobiles, no helicopters and maybe not even dog sleds to move supplies and equipment. Yet a straight line from “nowhere to nowhere,” crossing two mountain ranges and at least three major rivers, had to be surveyed and clear cut. Now, fast forward to the present: Taking the border crossing as a reference point for indexing Google Earth®, the “clear cut” made roughly 100 years ago shows up on the satellite photography for most of its many miles. Google would however place the 141º meridian several seconds of arc to the east! Even though referenced for the last 183 years, the 141º meridian is now a hot topic of discussion between the U.S. (State Department) and their equivalent Canadian lawyers. All this because of actual and perceived vast deposits of oil and gas in the Arctic Wildlife preserve and out into the Beaufort Sea towards the North Pole, for yet another about 1,221 nautical or about 1405 statute miles. Stay tuned!

Major References:

Bedini, S. Jefferson and Science. Chapel Hill: University of North Carolina Press, 2002.
International Boundary Comm. Publications: www.internationalboundarycommission.org
Project Gutenberg. International Meridian Conference, Washington, DC, October 22, 1884. www.gutenberg.org/etext/17759
Natural Resources Canada Centre for Cadastral Management. Manual of Instructions for the Survey of Dominion Lands.
Van Zandt, F.K. Boundaries of the United States and the Several States. Government Printing Office: U.S.G.S. Bulletin 1212, 1966.
This article first appeared in Side Shots, journal of the Professional Land Surveyors of Colorado, August 2008: Vol. 39, No. 3.