Lot

In the Public Land Survey System (PLSS), a lot is a legal subdivision of a section that is not an aliquot part. It is identified by a number, such as "lot 2," instead of by fractions like NE1/4SW1/4.

BLM's Glossary of Surveying and Mapping Terms defines a lot as "a subdivision of a section which is not described as an aliquot part of the section, but which is designated by number." A lot "may be regular or irregular in shape and its acreage varies from that of regular subdivisions." The term "government lot" is common outside BLM. "Lot" is also the name for parcels in recorded private subdivisions, which is a different thing.

Why lots exist

Sections do not always divide evenly. BLM's Manual of Surveying Instructions (2009) explains where lots come from:

• The sections along the north and west boundaries of a township absorb the township's excess or deficiency in measurement. Each of them except section 6 has four regular lots, and section 6 has seven (sections 3-32 and 3-103)
• Sections invaded by meanderable bodies of water, or by approved surveys at variance with the regular subdivisions, are divided into "as many aliquot parts as possible and then lots" (section 3-106). BLM's Specifications for Descriptions of Land (2017) illustrate this with a section lotted around mineral surveys

Numbering and size

Lots are "numbered in a series progressively from east to west or from north to south in each section." In section 6 they run from No. 1 in the northeast, west to No. 4 in the northwest, and south to No. 7 in the southwest (section 3-103). Regular lots along the township boundary are returned as 40 acres plus or minus the excess or deficiency (section 3-32). The Manual advises avoiding lots under 10 or over 50 acres where a lot has a full 20-chain width, and under 5 or over 45 acres for compact lots along a meander line (section 3-105).

Describing lots

Under the Specifications:

• A lot is written with its section, such as "sec. 3, lot 1," and lots are listed before aliquot parts
• A lot is not an aliquot part and is not described by fractions. Halves or quarters of a lot are ambiguous because the division line is uncertain
• To divide a lot, "an official survey will be conducted or a supplemental plat will be prepared with lot numbers assigned"

The Manual adds that once the official plat is filed, "further subdivision of lots can only be accomplished by survey or supplemental plat" (section 3-104).

Why it matters for mining claims

Lots appear wherever the grid meets irregular ground: township edges, rivers and lakes, and earlier surveys. BLM's glossary notes that supplemental plats are also required to show land segregated from the public lands by later surveys of patented mining claims and other private land. A lot number means nothing without the plat that created it, so mining claim research has to use the current official plat or supplemental plat for the section.