By Rectangular System
In the early days (from 1785) of the United States,
provisions were made to subdivide territorial lands
into townships and sections thereof, along lines
running with the cardinal directions of north-south,
east-west. Later, as additional lands were added to the
public domain, such lands were subdivided in a
similar manner.
However, these methods of subdividing lands do
not apply in the eastern seaboard (original 13 states)
and in Hawaii, Kentucky, Tennessee, Texas, and West
Virginia. For laws regulating the subdivision of public
lands and the recommended surveying methods, check
the instruction manual published by the Bureau of
Land Management, Washington, D.C.
By Plane Coordinates
For many years the triangulation and traverse
monuments of various domestic and foreign survey
agencies have been defined by their geographic
positions; that is, by their latitudes and longitudes.
Property corners might be definitely fixed in position
in the same way. The necessary computations are
involved, and too few land surveyors are sufficiently
well versed in the theory of geodetic surveying for this
method to attain widespread use. In recent years, plane
coordinate systems have been developed and used in
many states and in many foreign countries. These grid
systems involve relatively simple calculations, and
their use in describing parcels of land is increasing.
Every state in the American Union is now covered by
a statewide coordinate system commonly called a grid
system.
As with any plane-rectangular coordinate system,
a projection employed in establishing a state
coordinate system may be represented by two sets of
parallel straight lines, intersecting at right angles. The
network thus formed is the grid. A system of lines
representing geographic parallels and meridians on a
map projection is termed graticule. One set of these
lines is parallel to the plane of a meridian passing
approximately through the center of the area shown on
the grid, and the grid line corresponding to that
meridian is the Y-axis of the grid. The Y- axis is also
termed the central meridian of the grid. Forming right
angles with the Y- axis and to the south of the area
shown on the grid is the X-axis. The point of
intersection of these axes is the origin of coordinates.
The position of a point represented on the grid can be
defined by stating two distances, termed coordinates.
One of these distances, known as the X-coordinate,
gives the position in an east- and -west direction. The
other distance, known as the Y-coordinate, gives the
position in a north- and- south direction; this
coordinate is always positive. The X -coordinates
increase in size, numerically, from west to east; the
Y -coordinates increase in size from south to north. All
X -coordinates in an area represented on a state grid are
made positive by assigning the origin of the
coordinates: X = 0 plus a large constant. For any point,
then, the X -coordinate equals the value of X adopted
for the origin, plus or minus the distance (X´) of the
point east or west from the central meridian (Y -axis);
and the Y -coordinate equals the perpendicular
distance to the point from the X -axis. The linear unit
of the state coordinate systems is the foot of 12 inches
defined by the equivalence: 1 international meter
= 39.37 inches exactly.
The linear distance between two points on a state
coordinate system, as obtained by computation or
scaled from the grid, is termed the grid length of the
line correcting those points. The angle between a line
on the grid and the Y -axis, reckoned clockwise from
the south through 360°, is the grid azimuth of the line.
The computations involved in obtaining a grid length
and a grid azimuth from grid coordinates are
performed by means of the formulas of plane
trigonometry.
A property description by metes and bounds might
include points located by coordinates as follows:
“Commencing at U.S. Coast and
Geodetic Survey Monument ‘Bradley,
Va’, having coordinates y = 75,647.13 ft
and x = 35,277.48 ft, as based on the
Virginia Coordinate System, North
Zone, as are all the coordinates, bearings,
and distances in this description; thence
S 36°30´E, 101.21 ft to the intersec-
tion of Able Street and Baker Avenue,
whose coordinates are y = 75,565.77 ft
and x = 35,337.45 ft, . . . .”
By Blocks, Tracts, or Subdivisions
In many counties and municipalities the land of
the community is divided into subdivisions called
blocks, tracts, or subdivisions. Each of these
subdivisions is further subdivided into lots. Blocks
and tracts usually have numbers, while a subdivision
usually has a name. Each lot within a block, tract, or
subdivision usually has a number.
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