Township

In the Public Land Survey System (PLSS), a township is the unit of survey: a nominal square about six miles on a side containing 36 sections. "T. 4 N." names the fourth row of townships north of the base line.

BLM's Glossary of Surveying and Mapping Terms defines a township as "the unit of survey of the public lands; normally a quadrangle approximately 6 miles on a side with boundaries conforming to meridians and parallels within established limits, containing thirty-six sections, some of which are designed to correct for the convergence of meridians or range lines."

Two meanings

BLM's Specifications for Descriptions of Land (2017) note that "two different meanings have been applied to the term 'township.'"

1. A row: "a series of nominal 6-mile-wide horizontal rows north and south of the base line"
2. A square: "the nominal 6-mile-square area that is situated between two adjacent range lines and two adjacent township lines"

The legal basis

Federal law requires the public lands to be divided "by north and south lines run according to the true meridian, and by others crossing them at right angles, so as to form townships of six miles square," and the corners of the townships "must be marked with progressive numbers from the beginning" (43 U.S.C. 751). BLM's Manual of Surveying Instructions (2009) numbers townships "to the north or south commencing with number 1 at the base line" (section 3-3).

How a township is surveyed

• The exteriors come first. The south and east boundaries are normally the governing lines of the subdivision (section 3-17)
• Meridional boundaries are run south to north on true meridians, with quarter-section and section corners set alternately every 40 chains (section 3-18)
• The interior is divided into sections, with any excess or deficiency placed against the north and west boundaries (Specifications)
• Standard parallels every 24 miles restart full measurement to take up the convergence of range lines (section 3-13)

Township lines

The glossary explains that the east-west boundaries are "township lines" and that, by law, "they were intended to be on true parallels of latitude." The north-south boundaries are range lines.

Fractional townships

Not every township has 36 full sections. The glossary defines a fractional township as one "containing less than 36 normal sections," usually because of a segregated body of water, land that cannot be surveyed as part of the township, or the closing of the surveys on a state boundary or other limiting line.

Writing it

The Specifications use "T." for one township and "Tps." for more than one, as in "Tps. 4 and 5 N., R. 14 W." The meridian must be named, because the same township numbers repeat under every principal meridian.

Why it matters in research

The township is the unit that official plats, master title plats, and mining claim indexes are built on. The township plat, not an idealized grid, shows what its sections and lots actually contain.