Early Public Land Survey System (PLSS) Plats

The Public Land Survey System was set up by the Northwest Act of 1799. It provided a uniform method for describing land based on a grid aligned to a baseline. In Washington and Oregon the baseline is the Willamette Meridian which passes through Portland, OR. From there a grid is laid out to define townships, an approximately six mile by six mile square which is further divided into 36 sections, each approximately a mile on each side.

thumb|400px|Illustration of the system from the National Atlas [1] The townships are numbered by their relative position from the William Meridian. Reardan itself is in a Township designated T25N R39E, which means Township 25 North Range 39 East, or the 25th row of townships north and the 39 column east of the Willamette meridian.

Sections are numbered in a special way, starting from the north east corner of the township is section 1. To the west of it are sections 2, 3, 4 ,5 and finally 6 on the western boundary of the township. The next section 7, is immediately south of section 6. The remaining sections are numbered in this serpentine fashion. Every section is physically adjacent to the sections numerically adjacent. This method of number is called Boustrophedon.

The reason that the measurement is approximate if that the earth is round so that "parallel" north-south lines get closer together as you get closer to the poles. Typically the southeast corner of the township is laid out first and from there, the outline of the township is established and then the sections within the township. This is done astrologically or by determining position from the stars. The sections on the western and northern edges of the township are adjusted to fit the astrological boundaries of the township, so these sections may not be one mile by one mile.

Around Reardan this is quite apparent in the boundary between townships in Range 24 N and Range 25N. There is an "adjustment" of the north-south section lines at this interface of about 100 feet. Also the northern sections of Range 24N are substantially larger than other sections making them approximately 1-5/8 mile by 1 mile. This happens again just south of Sprague between Range 20N and 21N. Here the shift is much greater and the size of the sections is reduced to a little over a half mile by a mile.

Reardan grid:

Caption text

Township	R37E	R38E	R39E	R40E	R41E	R42E
T27N		T27N R38E	T27N R39E	T27N R40E	T27N R41E
T26N		T26N R38E	T26N R39E	T26N R40E	T26N R41E	T26N R42E
T25N		T25N R38E	T25N R39E	T25N R40E	T25N R41E
T24N		T24N R38E	T24N R39E	T24N R40E
T23N	T23N R37E	T23N R38E	T23N R39E
T22N	T22N R37E	T22N R38E	T22N R39E