Here's another long-awaited installment of my Shovelbums Guide Series. If this post helps you or increases your knowledge in anyway please repost or give it a retweet. Thanks!
Archaeologists on the West coast, in many of the plains and central states, Alaska, and Hawaii are likely familiar with the Township and Range system. Here in the Great Basin and in surrounding states the “legal location” of a project area or an individual site is given in quarter quarter sections using the Township and Range System. But, what is the system and where do we get coordinates like T17N, R15E, Mount Diablo Meridian? Well, I’m glad you asked. I’ll start with a short history of the rectangular survey system, also known as the Public Lands Survey System (PLSS).
The PLSS was originally proposed by Thomas Jefferson. It began after the Revolutionary War ended and the Federal Government became responsible for massive areas of land west of the original thirteen colonies. The government wanted to distribute land to Revolutionary War soldiers in reward for service and they wanted to sell land as a way to raise money. Before this could happen the land needed to be surveyed.
Two laws helped create the PLSS as we know it today (well, up until 1973, anyway). The Land Ordinance of 1785 provided for the systematic survey and marking of public lands. Apparently it took two years to figure out how to actually accomplish that because in 1787 the Northwest Ordinance established a rectangular survey system to give coordinates to the land parcels. The PLSS has been in continuous use since 1785 and is the basis for most land transfers and ownership today. The current procedures for accomplishing the PLSS were set down in the Manual of Instructions for the Survey of the Public Lands of the United States in 1973.
Not all land was included in the survey. Lands not surveyed included beds of navigable bodies of water, national installations (military, parks, etc.), and land grants already in private ownership.
According to the Bureau of Land Management’s website almost 1.5 billion acres have been surveyed for the PLSS to date. The BLM is the record keeper for over 200 years of survey information, which often includes the original surveyor's notes and hand-drawn maps.
Now that we know how it started, let’s talk about exactly what the PLSS is and how we get to township and range coordinates.
As stated above, the PLSS is used to divide public land. Since the system was started after the Revolutionary War it mostly only applies to new land that was acquired after that time. That’s why none of the thirteen original states were included: there was little public land left.
The PLSS divides land into 6-mile square townships. The townships are then divided into 36 sections. The sections can then be divided into half, quarter, and quarter quarter sections. It may not make sense that the quarter quarter sections aren’t 1/16 sections but once you write it out and use the system it seems to work. The sections are number starting in the northeastern corner and continue right to left. The numbers snake down going left to right (7 through 12) in the second row then back the other direction and so on. The section numbers end at 36 in the southeastern corner. Each section is usually 640 acres or one-mile by one-mile square. It makes it really easy to do block surveys in the West, that’s for sure.
The township and range coordinates are based on regional meridians and baselines, 37 of them. Range is designated east and west of the Principle Meridian for the region and Township is designated north and south of the baseline. When reporting the location of a parcel of land using township and range it’s necessary to include the Principle Meridian. For much of California and all of Nevada the Principle Meridian runs through Mt. Diablo in California. So, a proper land designation for somewhere in Nevada would be, Nevada, Mt. Diablo Meridian, Township 21N, Range 15E, Section 35.
There are several areas of the country where this system is different for various reasons. In Ohio and Indiana, where the surveys started, the townships are 6 miles square. The surveys are named, but the names are not named based on the principle meridians, and the numbering system and starting points are different. In Louisiana things really get crazy. They are based on parcels of land known as arpent sections and they pre-date the public surveys. An arpent measures 192 feet and a square arpent, confusingly called an arpent, is about 0.84 acres. The parcels are designed to give settlers living on waterways beachfront property and tillable, farmable land. So, they are oddly shaped. French arpents were two to four arpents wide and 40 to 60 arpents deep. Spanish arpents were 6 to 8 arpents wide and 40 arpents deep. Section numbers frequently exceed 36. I can’t continue. It’s just too crazy. If you plan to work in Louisiana find out how it all works. You’ll be smarter and happier for it.
Now you should be an expert on the public land survey system. When someone says the site is located in T17N, R15E of the Mt. Diablo Meridian you’ll know what that means. I’ll admit that I was out in the West for quite a while before I really knew what the township and range system really meant. Find out where your principle meridian originates from and impress your friends.
Thanks for reading and I’ll see you in the field.