The Jefferson Grid

Thank you to GEB reader Clare for pointing us to this story about the Jefferson Grid. The Jefferson Grid refers to the Public Land Survey System (PLSS) or the Rectangular Survey System used in many parts of the United States to plat, or divide, real property for sale and settling.

Anyone who has looked around the US has noticed that large parts of it are divided up into squares, one mile to a side, often highly visible in satellite imagery and often sporting irrigation circles. The article linked above explains why that is and some of the history behind it.


The state of Iowa is just a sea of squares.


Irrigation circles in Idaho, one in each square.

As you can see above this is not the most efficient use of the land and in some cases farmers have inserted smaller circles in between the larger ones. The most efficient layout of identical sized circles is the honeycomb pattern seen below:


This honeycomb irrigation pattern found near Boardman, Oregon, is actually quite rare.

You might think at first that the Jefferson Grid is a universal uniform grid covering the whole of the US, but as you can see on Wikipedia there are actually a number of different regions, each with its on reference lines and the different regions do not necessarily line up with each other. Also, due to the fact that there were no GPS’s at the time the original surveying was done, there are quite a lot of errors in the grids and it is not uncommon to see an area like the image below where things are not quite straight:


Parallelograms

The use of a grid is also not unique to the USA. Here is an area in Mexico that also uses a neat squared grid, except they use the metric system, so each square is two kilometres to a side.


A grid system in Mexico.


Many parts of the world such as Zambia, above, do not use a grid system.

For the locations featured in this post download this KML file.

Many cities around the world also have grid patterns highly visible from above, but perhaps that is a topic for another post.

About Timothy Whitehead

Timothy has been using Google Earth since 2004 when it was still called Keyhole before it was renamed Google Earth in 2005 and has been a huge fan ever since. He is a programmer working for Red Wing Aerobatx and lives in Cape Town, South Africa.






PLEASE NOTE: Google Earth Blog is no longer writing regular posts. As a result, we are not accepting new comments or questions about Google Earth. If you have a question, use the official Google Earth and Maps Forums or the Google Earth Community Forums.

Comments

  1. I Have Windows 10 And Can Not Get Google Earth To Download. Can Anyone Tell Me Why ?

  2. Interesting article. I live in South Louisiana, and the land use system here was French influenced and thus, plots of land are very long and narrow. The plots are called vacheries, which is also the name of a town along the river. Type vacherie into the GE search and you can see this phenomena very clearly. A friend who ranches nearby told me he has a plot of land 200 feet wide and a mile long.

    • There are a couple of spots in Michigan laid out on the French system, including the wards of the City of Detroit. You’ll also find a few around Monroe and Cheboygan. Otherwise, it’s the standard grid, with some of the surveying done by George Washington himself.

      • There are areas within Metro Detroit where the PLSS and French grids intersect, resulting in interesting contractions with the street grid. For example, observe the streets around the area of Warren and Livernois or McNichols and Gratiot.

  3. There is also the problem of the longitudinal lines getting closer to each other as you approach the poles. Michigan has 5 or 6 “correction lines” where the survey crews started over from scratch. The grid continues all the way to Lake Superior, but in areas where agriculture didn’t develop, the grid isn’t reflected in the kinds of features visible on GE.

    Wisconsin has a lot of crooked section lines. I think the surveyors avoided lakes and swamps.

  4. The honeycomb pattern is the most efficient use of land, but when farming places where you need artificial irrigation such as the center-pivot circle systems you showed, it isn’t maximizing land use that you care about, but maximizing water use. Or in other words, in lots of places there’s far more arable land available than there is water to use on that land, so the inconvenience of bucking the grid system to make honeycombs of irrigation pivots doesn’t buy you anything. My inner organic hippie suggests this is probably a good thing, because the more common grid pattern leaves larger fallow sections for native species.

  5. “Also, due to the fact that there were no GPS’s at the time the original surveying was done, there are quite a lot of errors in the grids and it is not uncommon to see an area like the image below where things are not quite straight:”

    You neglect to mention the major reason the grid systems eventually become untidy. You cannot lay out north-south running parallel lines indefinitely, because they ultimately get squeezed by the lines of longitude, which are not parallel, but always run true north-south. Actually, I’ve always been mighty impressed by how accurately those old boys were able to run lines using their chains, transits, and other gear ( http://www.surveyhistory.org/the_surveyor's_basic_tools.htm) over real estate that was often more vertical than horizontal, and yet they produced nearly perfect square miles.

    Japan (at least the rice growing parts near the capital) was laid out in grids in the 7th century. The squares have gotten wobbly over the centuries, but they can often be seen in Google Earth in the Nara Basin. (See: http://www.hgeo.h.kyoto-u.ac.jp/soramitsu/jori.html ) The units of length are different, of course, but it’s interesting that the grid is 6 by 6 units, and was counted back and forth, but just like the Japanese writing system, they started on the wrong side and went in the wrong direction.

  6. Google map has some sort of trouble in my locality too.



PLEASE NOTE: Google Earth Blog is no longer writing regular posts. As a result, we are not accepting new comments or questions about Google Earth. If you have a question, use the official Google Earth and Maps Forums or the Google Earth Community Forums.