The establishment of the PLSS by crews of surveyors hired by the Federal Government followed a standard set of rules. Put simply, the surveyors first laid out the exterior of "townships" nominally 6 by 6 miles, and numbered them by tiers (going north), and by ranges (east or west of a dividing line). Then, at a later date, a different surveying crew divided each township into 36 numbered "sections" (each nominally 1 mile square).
The numbering of sections begins in the northeastern corner of a township, runs westward, then snakes back and forth, ending in the southeastern corner. Even if a township is partial (e.g., the place where section number 1 would normally fall is under Lake Michigan), the section numbering follows the standard as though a full township were being surveyed.
Each section's boundary was marked by eight monuments. Areas under water were not surveyed. The entire survey in Wisconsin was finished in about 30 years beginning in 1832; progress was roughly northward from the state's southern border.
and acreages will vary.
A PLSS section is usually approximately square. Except where water bodies interfere, each section usually has eight monuments defining its boundary. Corners were marked originally with wooden posts. Later efforts to re-mark these points sometimes used rock piles, iron pipe, et al. Corner locations were further documented by reference ("ties") to nearby objects.
Four corners are "sections corners" and the other four are approximately half way between the section corners and are called "quarter corners". The center of the section was not monumented; instead, its location is inferred, usually by intersecting lines connecting the opposite quarter corners.
Of course, surveying equipment and techniques in the 19th century could not achieve the accuracy levels that are normal today.
Especially in the northern part of the state, where difficult field conditions such as magnetic-field anomalies and extensive wetlands confronted the survey crews, some sections ended up being far from square.Sections were surveyed starting in the southeastern corner of a township; each such "interior survey" laid out the sections with as much accuracy as possible and then accommodated discrepancies with the earlier "exterior survey" only along the periphery of the township. As a result, the northernmost and westernmost set of quarter-quarter sections in a township are most likely to deviate from the area goal of 40 acres.
Townships are identified by numbers that increment about every 6 miles going north, and every 6 miles going east or west. There are 53 tiers of townships going north, and 51 ranges going east (30) or west (21) from a north-south line called the Fourth Principal Meridian.
The Fourth Principal Meridian starts on the southern state border about 12 miles east of Dubuque, Iowa and forms the common boundary of modern Lafayette and Grant counties. Then it continues more or less northward approximately 282 miles to the shore of Lake Superior at a point just west of the mouth of the Montreal River in Iron County. Finally, the meridian reappears on Outer Island for about four additional miles.
Township nomenclature
The standard way of describing a township uses the tier number (and direction,
which is always north), range number, and range direction. For example, T4N
R7E or T13N R6W. Note that because Wisconsin is not rectangular, quite a
few combinations of tier/range/direction do not apply. For instance, T13N
includes Ranges from 7W (in Vernon County) to 23E (in Ozaukee County), while
farther north T30N extends from Range 20W (in St. Croix County) to Range 28E.
As a result, there is no township named T13N R8W (which would be in Iowa) or
T13N R25E (which would be in Lake Michigan.
Note that civil towns, which are units of local government, should not be confused with PLSS townships, even though in most of the sourthern and central parts of the state the two often occupy the same area. Rural areas in the north are often divided into civil towns made up of multiple PLSS townships.
Due to the earth's curvature, a series of lines surveyed to the north tend to slowly converge with each other. Applying this effect to the PLSS, the townships in each succeeding tier going north become narrower in the east-west dimension. To adjust for this convergence, the 6-mile width of townships was re-established at each of five "correction lines" as the survey progressed northward. As a result, the townships and sections on opposite sides of a correction line do not line up with each other except at the Principal Meridian.
Historical sequence
The PLSS in Wisconsin was put in place essentially continuously beginning in
1832 and concluding in the north in the 1866. Township boundaries were surveyed
first; sections were filled in later. A variety of contractors did the work
for the General Land Office (GLO). Surveyors followed written "Instructions"
from the Surveyor General (located in Cincinnati, OH through 1839, then relocated
to Dubuque, IA); instructions changed through the years. A field crew typically
was composed of a deputy surveyor (the crew chief), two chainmen (since the
distance-measuring device of the day was a chain measuring 66 feet), an axeman/marker,
and (in open country) a flagman.
The survey crews' work was documented in field notebooks. The original notebooks are in custody of Wisconsin's Board of Commissioner's of Public Lands. Microfilm copies are held at the State Historical Society. The original notebooks were scanned in 2001 and are viewable over the Internet through a cooperative project of BCPL and the University of Wisconsin-Madison's General Library System. Due to yellowed paper, faded ink, the florid style of penmanship common during the 19th century, and the use of surveying terminology (often abbreviated), it may be difficult for many people to easily understand the contents of the field notebooks. There is no known comprehensive digital text version of the notebooks; some pages may have been transcribed but there is no index or summary to assist in locating them. Hand written copies were provided to each county around 1900, but these copies may not be retrievable in any particular case.
Landscape observations
The surveyors not only marked and documented the PLSS as they installed it.
They also generally described the countryside and, more specifically, noted
the crossing of streams, wetlands, blown-down timber, etc. When setting corners,
they often relied on nearby trees as references to the location of the corner.
Collectively, these landscape observations represent the earliest systematic
information about the state's vegetation. Careful study of the notebooks can
be used to construct vegetation data, although due to the wide spacing between
corners it may be impossible to infer what vegetation existed at other points.
An interpretation and manual compilation by Finley resulted in a 1:500,000-scale
map ("Map of the Original Vegetation Cover of Wisconsin") published in 1976.
A more recent interpretation by a
project at the Univ. of Wisconsin-Madison's Forest Ecology and Management Dept.
is viewable as a map over the web.
Original plat maps
GLO employees in the Surveyor General's office worked from the field notes
to draft maps of the PLSS townships shortly after the surveys were done.
These "original plat maps", which are held by BCPL, have been scanned and
are available on CD-ROM
(one per county); these maps may also appear on the Internet in the future.