Demystifying Parcels

Depending upon where in the US you map, different and often duplicate terminology is used. In Texas, for example, the reference land grid is the “Original Texas Land Survey” or OTLS featuring not only Blocks, Surveys and Abstracts, but also a separate and unrelated reference grid of Subdivisions, Lots and Tracts. These are surveys established hundreds of years ago that do not change ownership.

Parcel layer found in Travis County, TX Abstract Number A-7; Survey Name: TJ Chambers

Thirty states use the Public Land Survey System. The PLSS consists of township and range units (consisting ideally of 36 square sections arranged in one-mile square blocks six wide by six tall). Within each section, there are subdivisions: government lots (which may be lettered or numbered) or quarter quarters (1/16 of a section representing 40 acres). Sometimes, and for a variety of reasons, there are patented mining claims and additional government plots of land with no rhyme or reason we term “tracts.” The PLSS is also a reference grid, and the constituent parts do not have a concept of ownership these days. Confusingly, the terms “section” and “township” also have some application in Texas, typically in West Texas, but they are not the same as in the Public Land Survey System.

Parcel layer found in Del Norte County, CA Meridian 15 Township 16 North, Range 1 West, Section 17

The remaining states (with a few exceptions mainly along the East Coast) use no reference grid and instead have parcel data coverage only. Each parcel is surveyed using metes and bounds (bearing and distance) notation. The parcel where your home is located is an example of the type of parcel data we offer, and it is compiled from more than 3400 counties nationwide. Contrasted with reference grids, parcels are commonly bought, sold, subdivided and merged. Each county assessor typically creates a file of land parcels for their county and then makes it available either as a hard copy or digital map. The digital data either contain points representing the approximate location of the parcel or the true polygonal outline of the parcel. WhiteStar compiles these data into a sensible whole using a common data model and then makes them available via WhiteStar Cloud.

In each instance, duplicate terminology abounds. In Texas and always in the Public Land Survey States, parcel legal descriptions may reference the underlying reference grid. Therefore, when you hear the term “lot” you first must determine the state you are mapping, the type of reference grid in use (if any) or whether it’s a metes and bound state.

Previous
Previous

When Squares Aren’t Enough: Mapping Lots, Tracts, and Quarter-Quarters

Next
Next

Building a Business Case for GIS Data