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The Prairie Dominion Land Survey System

If you are researching your family history and reading about Canadian prairie homesteads, you will likely encounter the terms "Townships", "Ranges" and Sections". These terms were used in the Canadian Dominion Land Survey (DLS) system of 1871 to describe the measurement and subdivision of land in Western Canada, much of it just then, only recently acquired from the Hudson's Bay Company. This web page will focus on a few simplified diagrams created to clarify the terminology, structure and basic mechanics of the DLS. A subsequent web page will look at a number of actual historic maps and documents describing and depicting the implementation of this survey system.

The 49th Parallel Boundary Commission Survey and the Dominion Land Survey were both initiated almost coincidentally between the years 1871 and 1872, the surveyors occasionally collaborating and even sharing resources (Link). The Canadian prairie was essentially isolated from eastern Canada at that time despite the existence of the difficult Dawson overland route to the Red River from Thunder Bay. The survey teams chose instead to transport their equipment and supplies through the United States, first by rail from Duluth to the Red River, then by ox cart and flat river boat to their destination at the then-assumed international border, south of modern day Winnipeg. To commence the surveys, it was necessary to first determine the precise locations of the 49th Parallel and the First Principal Meridian, the two most basic elements of the survey that would serve as anchors or main horizontal and vertical reference lines for the surveys themselves. The two survey teams collaborated to attempt this task just south of the border at Pembina, which in a sense, became the "Ground Zero" of both surveys.

Today, this small American town, coupled with Emerson, its counterpart on the Canadian side, continues to be a very significant border crossing between Manitoba and North Dakota. A thriving little town, it formerly housed an assembly plant for the Winnipeg-based Greyhound Bus Company in the 1960s, and the facility now assembles modern luxury MCI coaches for the American market. In the oxcart era, the Hudson's Bay Company maintained a trading post north of the border, while on the American side, small as it was, Pembina housed a military garrison, and as such, it was at the northern terminus of a 900 hundred mile telegraph line from Chicago. View Photo


Electro-telegraphy was only an emerging technology in the 1860s, but it looked promising as a means of verifying longitudinal co-ordinates by transmitting and comparing accurate measurements of time between already established known locations and any other points on a common telegraph line. The surveyors were able to accomplish such a determination at Pembina via Chicago ... although just barely. A massive snow storm decimated the telegraph line shortly afterwards. The following link is a brief account of this event in the words of the actual surveyors (Link). Once Pembina's co-ordinates were confirmed, the surveyors used more traditional means to measure and precisely define the First Principal Meridian near Winnipeg, at 97 degrees, 27 minutes and 28 seconds West of Greenwich.

About Longitude and Latitude - Meridians and Baselines

We are all familiar with the geographical terms Latitude and Longitude used to define specific locations on a map or globe. The vertical lines of Longitude, or Meridians, are not in effect truly vertical. They converge at the North and South Poles, thereby pairs of meridians would enclose triangular wedge-shaped areas of the globe. The most important global longitude is called the Prime Meridian, arbitrarily located at Greenwich, England in 1851. This Prime Meridian is designated as the "zero degree" of longitude, all other lines numbered progressively higher moving westward from 1 to 360.

The Canadian DLS system however, designated 7 of its own additional Principal Meridians, the first of which is located a few miles west of Winnipeg. All other Principal Meridians are spaced approximately 4 degrees apart working westward (Fig. 01). An 8th meridian was also designated at the Pacific coast.

Lines of Latitude on the other hand, encircle the globe horizontally, east and west, parallel to the equator. Our 49th parallel international boundary is a line of latitude. The DLS designated certain other lines of latitude ... Base Lines and Correction Lines, spaced 12 miles apart beginning at the 49th parallel and ending north at the 60th parallel. Baselines and Correction Lines (red and blue Fig.02) are paired every 24 miles. Their significance and their 12/24 mile spacing is explained in subsequent paragraphs.

 

About Townships, Township lines, Range lines and Legal Descriptions

The ultimate purpose of the DLS was to subdivide the Canadian Northwest into manageable tracts of land suitable for family settlement and agriculture. The concept borrowed significantly from a pre-existing system in the USA which deemed that 160 acres of land were suitable for this purpose. The core or basic unit of the DLS system (and the US System) was a square plot of land called a Township measuring 6 miles by 6 miles on each side. Each Township could then be subdivided nicely into 36 smaller one square mile, 640 acre Sections, and further into smaller parcels of 160 acres.

Once any Principal Meridian was defined, highly qualified Dominion Land Surveyors would begin locating horizontal Base Lines and Correction Lines, both eastward and westward of the Principal Meridian, spaced 12 miles apart vertically. Between these lines, 12 mile square blocks of territory were then additionally defined as outlines to serve as containers for 4 smaller Townships, 6 miles square (Fig.04). The actual Township surveys themselves were contracted out to professional private surveyors, who were required to conform to guidelines in a new standardized Government surveyor's manual published in 1871. Each Township was to be defined by two horizontal Township Lines (Fig. 03 using 2nd Meridian) for its northern/southern boundaries, and two true-north-pointing meridians or Range Lines for its eastern/western boundaries.

The naming or Legal Description of any Township refers to its Township tier or row distance (Fig.03) counted northward from the 49th Parallel and its Range tier or row distance counted westward from a Principal Meridian. To complicate matters unfortunately, the term Township refers to the block of land as well as its relative northerly position. In our example (Figure 04), the Legal Description of the shaded Township left of the 2nd Principal Meridian is thus defined as Township 9, Range 3, West of 2nd Meridian, or more simply as 9-3-W2.

 

Sections, 1/4 Sections, Chains and Road Allowances

The following diagrams are closer views of Township 9-3-W2 referenced above showing 36 lower level numbered Sections, with a particular focus on Section 25 and its Quarter Sections. A section is approximately a square mile in size, encompassing 640 acres (259 hectares) and a Quarter Section 160 acres (65 hectares). Most prairie residents are quite familiar with the Quarter Section term as it describes the most common prairie parcel size originally allocated to pioneer homesteaders. All Quarter Sections are identified by their cardinal compass positions (NE or North East in our example) which are included at the beginning of their overall legal descriptions. Quarter Sections are also often subdivided into 16 yet smaller 40 acre (16 hectare) Legal Subdivisions, although they are not shown here.

The diagram labels show Township dimensions in Chains, a term derived from the use of Gunter steel chains as a means of measurement prior to the use of measuring tape. A Chain was (and is) 66 feet or 20.12 metres. A square mile Section (5280 feet or 1609.3 Metres) is thus 80 Chains by 80 Chains. Fractional dimensions are expressed as chain Links, there being 100 per Chain. A Chain and a half might be expressed as 1Ch. 50 or 1.5 Chains.

There were several upgrades to the DLS systems over the next few decades after 1871. Figure 05 shows a typical Township system in use between 1871 and 1881 (Systems 1 and 2) in which Road Allowances measured 1.5 chains and surrounded each Section. Figure 06 reveals a fairly dramatic change in Road Allowance dimensions and arrangement after 1881 (System 3). Road Allowances were now 1 Chain wide and 3 cross-township horizontal allowances were completely eliminated. As shown here, it is important to note that Road Allowances in the Canadian Survey System add rather than subtract to/from the overall dimensions or acreages of a Township measurement, as they did in the American PLS survey system. Also as you may have already noticed - all previous diagrams on this web page did not include Road Allowances for easier visualization and simplicity.


The Convergence of Meridians

The following two diagrams were adapted from an excellent University of Saskatchewan 1986 paper on the Dominion Land Survey well worth reading ... Understanding Western Canada's Dominion Land Survey System, by Robert B. McKercher and Bertram Wolfe.  It can be viewed online here (Link).

THE PROBLEM
A fundamental requirement of the Dominion Government's plan to subdivide the Northwest was that the final parcels of land be of equal size. The DLS Township grid system as depicted in our previous diagrams would seem to suggest that it may indeed have been the case. But in reality it's a bit more complicated because of a phenomenon commonly called the "Convergence of Meridians". All the above diagram vertical lines (including the Principal Meridians) are also true meridians and should be slightly tilting or narrowing toward the North Pole. But small diagrams are simply incapable of illustrating such small angles. The 1871 DLS surveyor's instruction manual shows a pair of township boundary meridians nearly perpendicular to their base at 89 degrees, 56 minutes, 52 seconds. The problem is illustrated in Figure 07-A in which the angle is obviously extremely exaggerated to demonstrate the effect. In this diagram there is only one complete full township, the lowest one at the Base Line, all others being clipped little by little northward to fit between the two converging meridians. If this systemic problem of convergence were not corrected, the township acreages would be gradually decreasing in size.

THE DLS SOLUTION - reveals the rationale for the existence of Base Lines and Correction Lines in the first place.

Figure 07-B demonstrates the DLS solution to the Convergence problem. The shrinking township convergence effect was restricted by design to only 4 townships at a time by special Correction Lines. Beyond such a line, the following northerly township would become full-sized once again and the subsequent townships would shrink until the next Correction Line, and the pattern would repeat itself. The resulting discrepancy in the width of the common boundaries between two townships straddling a Correction Line however would always produce a short "Jog".  Figure 09 below will later examine the significance of Base Lines which fall mid-way between two Correction Lines.

Figure 08 looks closer at Jogs and dimensions across 4 Ranges about 12 miles north of the 49th Parallel at the First Correction Line. Each Jog is shown becoming progressively wider moving west. The first Jog, J1 at the western edge of Range 1 is 225 feet wide.  Moving westward, you will notice that each subsequent Jog becomes wider than the previous one by 225 feet, and the same progression continues until the next Principal Meridian where the final Jog may be even more than one mile wide. The Saskatchewan paper referenced above explains the geometry of this progression in more detail.

Figure 09 is a direct tracing of a portion of Diagram 2 in the Appendix of the DLS surveyor's manual. Jogs and the convergence effect are illustrated more clearly over a wider field of view in this dimensioned detailed diagram, although the Jog numbers don't quite match those of the Saskatchewan paper. The westward progression however does appear to be the same. The Jog measurements are shown in red as Chains and black as Feet. Township dimensions are shown as 489 chains in this diagram, as they appear to include 1.5 Chain Road Allowances (as does our own Figure 05 diagram above).

Fortunately Range 2 Townships include northern and southern boundary dimensions enabling us to observe Convergence of Meridians and its correction in action. We can first observe that all township boundaries along Base Lines are a full 489 Chains. And if we begin at the 49th parallel at 489 Chains and move northward, the boundaries decrease until the First Correction Line, after which they are corrected to include a Jog and are even wider than a standard 489 Chain boundary (at 487.26c + 6.98c = 490.75c). They then shrink again to the next Base Line at 489 Chains and beyond until the next Correction Line and another Jog. This pattern repeats itself, although you will notice that the size of the Jog northward seems to have increased from 6.98c to 7.06c.

A copy of the actual old manual diagram can be viewed here (Link).

J.S. Dennis on Townships
J.S. Dennis, as Chief Inspector of Surveys, in charge of the publication of the 1871 Dominion Lands surveyor's manual, describes townships in the Appendix of his report in the Dominion Sessional Papers of 1892 as follows:

Form and Dimensions of Townships.

Townships are therefore quadrilaterals, having their east and west sides true meridians, and in length equal to six “sections " (that is six miles together with the roads), and having their north and south sides inclined at equal angles to these meridians, while the northern boundary is somewhat shorter than the southern boundary, these lengths varying from 480 chains plus the roads on the base line to about 180 links more on the next correction line south, and about 180 links less on the next one to the north. The angles of the township differ from 90° by about 4' only.

These are the theoretical dimensions and form of the township. Of course, the lengths of the lines and the magnitude of the angles may differ from theory from the effect of errors in surveying, but the closings on correction lines cut out these errors and prevent them from so accumulating as to materially deform the townships.

 

A 1919 topographical index map of the complete DLS survey

A monumental achievement for a young nation, the Dominion Lands Survey system in its entirety covered approximately 800,000 square kilometers (310,000 sq mi) encompassing approximately 178,000,000 acres. It is said to be the world's largest survey of its kind, laid down in a single continuous integrated grid.

The following topographical index map (Link) prepared a hundred years ago, reveals continued work on the survey in the northern regions of the prairies. It also depicts past and present work on the subdivision of townships and spirit levels (altitudes), base lines and meridians completed prior to 1919.