Topic 10.3: Government Survey System >

Learning Objectives

Iowa farmland aerial view showing the grid system.

After successfully completing this topic, you will be able to
• describe how the grid system works,
• list the hierarchy of sizes in the grid,
• write a legal description given a map of the subject property, and
• describe how to calculate the area in a parcel described by the government survey method.

History of the Government Survey System

The original 13  colonies were surveyed using the metes and bounds method. When the area of the United States began expanding rapidly at the end of the 1700s, government surveyors created a more efficient method to survey large tracts of land. The rectangular method overlaid  a grid pattern over the large land areas, describing parcels by their relationship to the grid.

More land in the U.S. is described by the government survey method than by any other method, and it is used in more than 30 states. The surveys established a series of meridians and base lines in many areas of the country which were the bases for the grid. This method works well for identifying large parcels, but not for describing small lots.

Sections, Townships, and Ranges

The basic north-south reference line in Florida is called the principal meridian. The basic east-west reference line in Florida is the base line. The lines originate in Tallahassee at the Principal Meridian Marker.

Principal meridians are lines running in a north-south direction and base lines run in an east-west direction.


Surveyors began by drawing north-south lines 24 miles apart called guide meridians. East-west lines 24 miles apart were called correction lines, or parallels. The squares 24 miles on each side formed by these lines are called checks.

Range lines run north-south every 6 miles. The north-south strip of land formed by two range lines is called a range.

Township lines run east and west every 6 miles. The east-west strip of land formed by two township lines is called a tier or township.


Additional lines within the checks are 6 miles apart and form smaller squares, called townships. A township is 6 miles square. A township has 36 square miles.

Section 14 in a township.

Section lines are made within the townships which are 1 mile apart. This created smaller squares called sections. A township has 36 sections. A section is one mile square and has one square mile.

The sections are numbered starting at the NE corner, and “snake” around. Section 36 is located at the southeast corner. Remember “SSS:” Sections Snake South.”

Click on the arrow below to continue listening…

Legal descriptions use the coordinate of the township and the range to exactly describe the township. The sequence in legal descriptions is “section, township, range.”

A section is divided into quarters, then quartered again until the rectangle is described.

To compute the number of acres in a description, multiply the denominators across, then divide the product into 640 (the number of acres in a section). If the description has an “and” in it, there are two parcels and each must be calculated separately.

How many acres are in the NW ¼ of the SE ¼ AND the S 1/2 of the NE  ¼ of Section 14?
If “and” is in the description, it means there are two separate parcels of land.

Parcel 1 acreage (NW ¼ of the SE ¼ ):
Multiply the denominators (bottom number) across: 4 x 4 = 16
Divide the product into 640— 
640 ÷ 16 = 40 acres in Parcel 1
Parcel 2 acreage (S 1/2 of the NE  ¼ ):
Solution: Multiply the denominators (bottom number) across: 2 x 4 = 8
Divide the product into 640
640 ÷ 8 = 80 acres in Parcel 2

There are two parcels of land in this description, divided by the “and.”
Parcel 1 has 40 acres
Parcel 2 has 80 acres
Total: 120 acres
Fractional sections and government lots

Sometimes a section is broken up by a lake or a river. If the remainder is smaller than one quarter of a section, it is called a “government lot,” identified by a specific number.

Other measurements
• a mile is 5,280 feet,
• a section has 640 acres,
• an acre has 43,560 square feet.