Flying over vast areas of the United States, especially across the Midwest and West, often reveals a striking pattern of squares and rectangles on the ground. This distinctive appearance is due to a systematic approach to land division established over two centuries ago.
The Public Land Survey System (PLSS)
The primary reason for the square patterns you observe from above is the Public Land Survey System (PLSS). This methodical system for dividing and mapping land was initiated by the United States government starting in 1785. Its purpose was to facilitate the orderly sale and settlement of public lands acquired by the young nation.
How the PLSS Creates Squares
The PLSS operates by establishing a massive, uniform grid across the landscape. This grid is based on a series of carefully surveyed north-south lines (called meridians) and east-west lines (called baselines). From these initial lines, the land is divided into progressively smaller, square-shaped units:
- Townships: The largest division, measuring approximately 6 miles by 6 miles, resulting in an area of 36 square miles. Townships are identified by their distance north or south of a baseline and east or west of a principal meridian.
- Sections: Each township is further divided into 36 individual sections, each measuring 1 mile by 1 mile, or 640 acres. These sections are numbered systematically within the township.
- Smaller Divisions: Sections can then be subdivided into halves, quarters, and even smaller parcels (e.g., quarter-quarter sections of 40 acres).
This hierarchical division creates the unmistakable checkerboard pattern visible from high altitudes.
| Unit of Division | Dimensions (Approximate) | Area (Approximate) |
|---|---|---|
| Township | 6 miles x 6 miles | 36 square miles |
| Section | 1 mile x 1 mile | 1 square mile |
| Section (acres) | - | 640 acres |
Geographic Extent of the Squares
The grid system of the PLSS covers a massive portion of the United States. It extends across approximately the middle third of the contiguous U.S., stretching from Ohio to the Rocky Mountains and from the Canadian border down to Mexico. This vast coverage ensures that the square pattern is a defining feature of the landscape in these regions. States like Kansas, Nebraska, Iowa, and large parts of California, Colorado, and Florida prominently display these geometric patterns.
Impact on the Landscape
The enduring legacy of the PLSS is evident in many aspects of the American landscape:
- Road Networks: Many roads follow section and township lines, creating a grid-like street pattern, particularly in rural areas and newer towns.
- Agricultural Fields: Farms are often laid out in square or rectangular fields, conforming to the boundaries established by the survey system.
- Property Boundaries: The system provides clear, legally defined boundaries for properties, simplifying land ownership and transactions.
- Urban Planning: Even some modern cities and suburbs, particularly in states surveyed under the PLSS, show remnants of this grid in their layout.
The precision and systematic nature of the Public Land Survey System have profoundly shaped the physical and economic landscape of much of the United States, making those aerial square patterns a testament to its historical significance.
