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| Map of the Public Land Survey System - US Dept of the Interior, Bureau of Land Management |
The next phase in restructuring the County data towards dependency on a more solid framework of geographic data consisted of building out the Public Land Survey (PLSS) layer. As noted in the previous chapter, the essential part of this work consisted of collecting Ground Control Points and Registered Land Corners for addition to their own respective layers.
Assembling all of the point data related to the Land Corners layer, numerous inconsistencies were noted, which required further investigation to understand their relevance to the situation.
Section corners appeared to have multiple locations along the eastern edge of the county, as well as along old Kansas City boundaries. Additionally, limited availability of data related to the boundaries along the river created challenges on that front, requiring in depth research to understand all of these issues and their relationship to one another.
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Downloading the PLSS layer from the Missouri Spatial Data Information Service (MSDIS) answered a few questions, but begged clarification on others. Partial sections adorned the eastern boundary of the County, and of the same Township/Range/Section as those adjacent in Clay County. What caused this?
The part of the County along the Missouri River valley had its own set of problems too. Some of the Township/Range information seemed to be completely wrong. Township/Range composed of 50s/30s dominated the County, but in this part of the County, 7/20s popped up along the river. Where did these come from?
While researching these questions, I came to know University of Missouri Professor and co-author of the “Atlas of Lewis and Clark in Missouri,” Jim Harlan. He developed the PLSS layer I downloaded, was very informative, and just a lot of fun to talk with. Validating much of what I already understood, he clarified a few other points as well.
The Platte Purchase of 1836 caused the issue along the eastern boundary. I am still not quite sure that I understand why the surveyors did not just pick up where they left off when they began their survey; instead, a slight jog remains today along the Platte County Boundary, where partial Sections of that part of the Township / Range meets partial Sections from the very same Township / Range in Clay County.
A lengthy technical discussion with Mr. Harlan did not exactly clarify the reasons behind the Sections mismatch, but did help me to understand the origin and impact. He attributed most of the issue and many other discrepancies I would soon uncover to excessive drinking on the frontier survey crews. Amusingly, it only took a little bit of reading to validate those conditions.
More easily understood, the sections along the Missouri River are a simple result of nature, which slipped my mind. Survey boundaries never move. The river does, and quite often. Most of Missouri is surveyed under the 5th Principal Meridian, while Kansas was surveyed using the 6th. Since that time, the Missouri River has wandered about quite a bit, leaving bits and pieces of what some perceive as other states on both sides of the river. This is most evident along the Mississippi River, but the Missouri has its own share too.
At least two mysteries were resolved, which only left the northern boundary of the County. That turned out to be a rather simple matter really. Everything was normal. The County boundary moved a few years prior, and several surveys were available, along with extensive documentation and precise GPS positions along the entire boundary.
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Following the framework identified in the previous chapter, I started construction on what would be four distinct layers. This actually took quite a bit of time, as I originally thought that I might just put it all together in one layer, but revelations associated with the Parcel Number, forced me down another path.
The Parcel Number identified the location of the land, indicating the Township/Range, the Section, the Quarter Section, as well as a couple other elements; indeed, the first 4 numbers in the set represented the legacy Map Sheet # that any parcel with that number could be found on. The second part of that number caused a little difficulty, but a little research uncovered that it was an old National Weather Service thing that has somehow found its way into the Parcel number; it covers 4 sections.
Example Parcel Number: 18–9.0–32–400–015–001.000
- 18 = Township 52 North / Range 33 W — 5th Principal Meridian
- 9.0 = Tetrasection 9.0
- 32 = Section 32
- 400 = Southeast quarter
- 015 = Block Number
- 001.000 = Lot . SubLot Number
Taking the Land Corners feature previously generated, along with the PLSS from MSDIS, I began tying corners to points. It was strictly a Section PLSS, and most of the corners on the PLSS did not move far, usually only a handful of feet in just about every direction. There were a few exceptions, and I decided it would be best to set those aside until completing more research on the specific attributes of those.
Once complete, I began developing the framework for the PLSS that would live on our system. It would be comprised of four independent layers. The current Map Sheet number already in use would carry through all layers.
The PLSSTownships defined the Township/Ranges for further division. PLSSFirstDivision was the first division of the Township/Range layer, and contained the Tetrasections. PLSSSecondDivision was the second division of the Township/Range layer, and contained the Sections. PLSSThirdDivision was the third division of the Township/Range layer, and contained the Quarter Section information.
Fields in each of the layers were named straightforward and simple, but still abbreviated. When developing these, I discovered that while you could give field names any number of characters, if you went to export any of them to a Shapefile the names were truncated. Consequently, all of the field names needed to be eight characters to provide clarity and prevent any confusion about the name.
Most of the data was numeric, or simple text. This attribute information would rarely, if ever change. The field definitions would always work, regardless of what changed though. I used Short Integer everywhere possible, as well as limiting the length of text fields. In the case of cardinal and ordinal directions, I simply created a domain (lookup table).
The layers do not contain all of the data for each of the division. They only hold that relevant to the County, which causes it to appear as if data is missing along the boundaries. There was just no need to define Sections that were not in Platte County though.
We left the boundary on the Missouri River alone. There was just no help for that. Surveys were more than 100 years old in some cases, or had never been properly located with GPS.
GPS positions identifying County boundaries on the north and east side of the County enabled us to re-define the boundary with 99% confidence. The work added hundreds of acres to County that had not been previously included or assessed, resulting in increased revenue for the County.
In the end, we only used the PLSSThirdDivision in our production environment. It had everything we needed in it. All of the other layers ended up being really for other cartographic purposes only and for analysis, and quality control. I simply made all adjustments in the PLSSThirdDivision layer, and migrated those changes up to the other layers once a month.
Building them out independently proved to be a good exercise that provided valuable insight when I started building the Subdivision framework. It helped in understanding the numerous peculiarities of working with DB2, ArcGIS, and ArcSDE, when building out new features and tables. It also provided an excellent understanding of the idiosyncrasies of the Public Land Survey System.
We decided not to involve too many parcel adjustments at this stage. There was more work to do and another framework to complete. New parcels that did not belong to subdivisions were subject to the new PLSS, and adjacent parcels adjust out of the way of them. Additionally, the individual receiving deeds in the Office of the Assessor began updating all associated parcels, where previously they had only reviewed the legal to determine location. This worked well for the remainder of my time there, and just updating as it came through resulted in updating nearly 75% of parcels in the County over 5 years.
All individual features were stored in a Feature Dataset named Public Land Survey System, along with the LandCorners and GroundControlPoints, due to their geographic relationship and dependencies.
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| Map displaying all layers of the grid and Land Corners |
Below are links to access the four new features created in this process. Full detail on the construction of these features is further defined within the Info Sheet, containing the Metadata, for each individual feature.
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- Info Sheet for PLSSTownship Metadata
PLSSFirstDivision feature (KML)
- Info Sheet for PLSSFirstDivision Metadata
PLSSSecondDivision feature (KML)
- Info Sheet for PLSSSecondDivision Metadata
PLSSThirdDivision feature (KML)
- Info Sheet for PLSSThirdDivision Metadata
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Coming next in the series … more data restructuring, Subdivision, re-alignment, and other points of interest!
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