Government Survey System

As with so many legal precepts, the government survey system was created by the U.S. in the wake of its triumph in the Revolutionary War. The newly independent United States found itself the owner of the area that now includes Ohio, Indiana, Michigan, Illinois and Wisconsin. The U.S. also found itself with serious debts incurred during the war.

So, the new government decided to raise revenues by selling parts of its new "northwest" territories to settlers. But the government couldn't use the old metes and bounds methods, because these new lands were essentially un-surveyed and it would take years (or decades) to do so with the old system.

Consequently, necessity forced the young U.S. government to create a rectangular survey system that was more easier and cost-effective to perform, as well as more precise. About three-fourths (3/4) of the continental U.S. now use this system.

The government survey system attempts to lay out a grid over the entire country, at least the parts that use this system. Parcels of real property are then surveyed and located relative to this grid of intersecting lines. This system employs four types of lines that are now part of our political and economic vocabulary:

  • Principal meridians. North-south lines that offer a principal north-south reference. There are 36 irregularly spaced principal meridians in the U.S., which usually sited from a substantial landmark, such as the mouth of a river. These meridians have been either numbered (such as First P.M., running north from the mouth of the Great Miami River separating Ohio and Indiana) or named (such as the Tallahassee Meridian and the San Bernardino Meridian). Parcels are referenced to a PM, though not necessarily the nearest one.
  • Base lines. East-west lines that offer a principal east-west reference, and which usually intersect a principal meridian at some prominent point.
  • Range lines. North-south lines (parallel to PMs) that are six miles apart and form ranges (the columnar area between range lines). With township lines, they establish square townships.
  • Township lines. East-west lines (parallel to base lines) that are also six miles apart. With the intersecting range lines, they establish townships. Since both range and township lines are six miles apart, each township contains 36 square miles (or 23,040 acres).



ange (Vertical) Lines

Township Lines

Base Line

Darkened square above is one township


As noted above, each township contains 36 square miles. These correspond to 36 sections. There is a uniform numbering system to sections, which begins with section 1 at the township's northeast corner and ending with section 36 at the township's southeast corner.

In each township, section number 16 is reserved as the school section. This section was chosen because of it central location. All or parts of this section can be sold, with the proceeds supposed to be directed for school use.






































S16 = School Section

Legal description

Each section is further divided into halves and quarters, commonly referred to as aliquot parts. The specific parcels being surveyed are normally described relative to aliquot parts.

When using the rectangular survey system, the legal description will follow a five-part format:

  1. Part of the section.
  2. Section number.
  3. Township row (sometimes, with the name of the township).
  4. Range column.
  5. Name or number of the principal meridian.

For example, the following is part of a sample legal description of a Chicago condominium, using the government system: "...the northeast 1/4 of section 4, township 39 North, Range 14, East of the Third Principal Meridian."

The following example is one section further broken down into aliquot parts and smaller parcels. The legal description indicates the portion and location within each section as follows:

1,320 feet (20 chains)

E 1/2 of NW 1/4 (80 acres)

2,640 feet

NE 1/4 (160 acres)

NW 1/4 of SW 1/4 (40 acres)

1,320 feet (20 chains)

E 1/2 of SW 1/4 (80 acres)

In its ideal state, the rectangular survey system assumes a flat Earth and accurate surveys. Unfortunately, that is not so. Early surveying equipment were adequate for the time, but were not always precise or accurate; and the range lines running true north-south are actually converging toward the north pole.

In truth, few if any townships are actually 36 square miles. The adopted standard for states using the rectangular system is to make township adjustments along its northern and western boundaries. That would be section 1 through 7 and 18, 19, 30 and 31.

Adjusted sections that are either undersized or oversized are typically titled fractional sections. If the adjusted section is smaller than a full quarter section (160 acres or 9 square miles), it is normally labeled a government lot and placed in a fractional section.

To compensate for the Earth's curvature, the rectangular/government survey system includes adjustment lines:

  1. Guide meridians. Every fourth range line is identified as a guide meridian. These are true north lines used in conjunction with intersecting correction lines.
  2. Correction lines. Also called standard parallel lines, every fourth township line is identified as a correction line. These correction lines are shorter than a regular township line.
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