Survey System
Township and Range Survey System Explained
The rectangular survey system — also called the township-and-range or government survey system — is used to describe land in most states west of Ohio. It's a frequent source of exam math questions.
How the System Works
The rectangular survey system was established by the Land Ordinance of 1785 to organize public land sales in the Northwest Territory. It divides land using two perpendicular reference lines: a principal meridian (north-south) and a baseline (east-west).
Ranges are vertical columns of land, 6 miles wide, measured east or west of the principal meridian. Range 1 East is the first column east of the meridian; Range 2 West is the second column west.
Townships are horizontal rows of land, 6 miles tall, measured north or south of the baseline. Each intersection of a range and township creates a 6×6 mile square (a township) containing 36 sections.
Key Measurements to Memorize
1 Township = 6 miles × 6 miles = 36 square miles
1 Section = 1 mile × 1 mile = 640 acres
1 Half Section = 320 acres
1 Quarter Section = 160 acres
1 Quarter-Quarter Section (40 acres) — the smallest standard unit
Sections are numbered 1–36, starting in the NE corner (section 1), moving west, then snaking back east on the next row
Section 6 is always in the NW corner; Section 36 is always in the SE corner
Practice Questions
Question 1
How many acres are in the NW¼ of the SW¼ of Section 14? (A) 10 acres (B) 20 acres (C) 40 acres (D) 80 acres
C — Start with 640 acres in a section. The SW¼ = 160 acres. The NW¼ of that = 160 ÷ 4 = 40 acres.
Question 2
In the rectangular survey system, how many sections are in one township? (A) 16 (B) 24 (C) 36 (D) 48
C — Each township is 6×6 miles and is divided into 36 sections of 1 square mile each.