Political Boundaries
Government Boundaries
The management of land within the US is based on political boundaries that have been established at the federal (1), state (50), and county (3,200) levels.
- Counties are usually responsible for administering parcels of land, including the authority to impose property taxes on landowners. Each county will assign a unique parcel number to identify each property, although it may occasionally change its numbering system. Property boundaries will always fit within a specific county. In some cases, county lines were established after property boundaries were originally defined. In those cases, the property will have been split into multiple properties so that each fits within a single county.
- State: County boundaries will always fit within a specific state. States can enact legislation that places certain controls over property within the state.
- Country: The Federal government also enacts legislation controlling the use of property.
National, state, and county boundaries can be considered static and well-defined.
Legal Descriptions
The area covered by a county is broken down into individual parcels (properties) that are recorded and managed by the county. To help with the administration of those properties, counties may be divided into smaller areas to form what is known as a legal description of a property. There are three different systems adopted by counties within the US: Government Survey, Metes & Bounds, and Subdivision.
Government Survey
This system was adopted by Congress in 1785 and remains popular in Western states. It involves establishing a grid
- Range: Range lines run north-south and are six miles apart. They are measured relative to 36 principal meridians for the US.
- Township: Townships run east-west breaking ranges up into areas that are six miles by six miles, and containing 36 sections
- Section: A one-square-mile block of land inside a township containing 640 acres. The sections are numbered from 1 to 36 starting in the NE corner of the section running left, then down one, running right on the second row before repeating.
- Quarter: Four quadrants of a section, designated as NW, NE, SW, and SE. Each quarter is approximately 160 acres.
- QuarterQuarter: Four quadrants of a quarter, approximately 40 acres.
Within ATTOM Cloud, the fields Range, Township, Section, Quarter, and QuarterQuarter can be found in the PropertyAddresses view and PropertyFeature table and can be used to identify and aggregate properties that use this approach.
Metes & Bounds
The Metes and Bound system is the oldest method of land measurement and consists of a defined point on the boundary followed by a series of steps that trace the outer boundary of the property.
In counties where the Metes and Bound system is used to define boundaries, there are no natural ways to group properties in larger areas based on the legal description. In these cases, it is better to use an alternate method such as Economic or Postal boundaries.
Subdivision (Lot and Block)
Some counties choose to divide the county up into a collection of County Subdivisions. These can then be further divided into Blocks, Lots, and Units and shown on a Plat Map (see below).
Within ATTOM Cloud, the fields Subdivision, BlockNumber1, BlockNumber2, LotNumber, and LegalUnit can be found in the PropertyAddresses view and PropertyFeature table and can be used to identify and group properties using this approach.