Introduction: The United States Public Land Survey (USPLS) started with the Land Ordinance of 1785 and covers all US land that was not settled by the time of the official government survey. It does not include the east coast states including Kentucky and Tennessee or Texas. Small areas of other states that were settled before the survey also technically excluded. This explains the odd shapes of many mining claims in the west. Latter title transfers followed USPLS lines.

Legal descriptions to 1 mile square sections have 4 parts: the State/Meridian, Township, Range and section number. Note that an official legal description always works from small to large areas, for example NW1/4, sec. 12, T.122N, R.71W, South Dakota, Fifth Principal Meridian.

• Meridian These are similar to UTM zones. Both apply to large areas based on a line of longitude, both are often left out of field data, and the position is not uniquely defined without them! The position of the principal meridian for any area, in contrast to UTM zones, is largely historical and arbitrary. The area governed by each Meridian, also in contrast to UTM zones, is irregular in size and shape, but it frequently follows state lines. Actually it is more correct to say that the states were formed according to the areas covered by the Meridians. Some of these areas include several large states while others include only a small part of a single state. Some of the smaller areas were caused by changes in tribal reservations. .
• Township These occur at 6 mile intervals east and west of the principal meridian. Township values are normally whole numbers starting at 1, but some exceptions occur. Township lines are normally adjusted every 4th line to correct for the spherical nature of the earth. These are called standard parallels.
• Range These occur at 6 mile intervals north and south of a base line that is associated with each principal meridian. The position of the base line for each principal meridian is also historical and arbitrary. Range values are normally whole numbers starting at 1, but some exceptions occur. Range lines are normally adjusted every 4th line to correct for the spherical nature of the earth. These are called guide meridians.
• Sections The intersection of Range lines and Township lines define 6 by 6 mile squares called Townships, which are divided into 36 sections. These are normally 1 by 1 mile squares, but some are altered to correct for the spherical earth. Most of these departures are pushed to the northern and western tiers of sections before the next standard parallels and guide meridians. Others are altered by simple survey errors. Note that old survey errors have legal precedence over new survey results so the odd-looking lines stay put. Section numbers always range between 1 and 36.

Township and Range: The numbers in red along the sides in the form T 24 N and along the top and bottom in the form R 7 E give coordinates in the Public Land Survey. The Public Land Survey system in the U.S. is called the "township-range" system. Each 24 square mile area formed by intersecting latitude and longitude lines is broken into 16 township-range units which in turn are broken into 36 one-mile square sections. This system allows every part of the U.S. to have a uniquely defined location. Figure 3 shows how this works.