Claim Density
The number of mining claims in a unit of area, such as a section or township, used to see where ground is being held and how that changes over time.
Detailed Definition
Claim density is a working measure: the number of mining claims in a unit of area, such as per section or per township. It shows where ground is being held under the Mining Law and, compared over time, where staking is increasing or falling off.
Choosing the unit
The PLSS provides natural units. BLM's "Specifications for Descriptions of Land" (2017) describes a township as "the nominal 6-mile-square area," subdivided into 36 sections, "each section being nominally 1 mile square, 640 acres." Counting by section or township matches how BLM records describe mining claims, "by state, meridian, township, range, section and by aliquot part to the quarter section" (43 CFR 3832.12(a)(1)).
Measuring it from BLM data
BLM publishes mining claim cases from MLRS as a layer of cases whose disposition is "anything other than closed" and a separate layer of closed cases. Its metadata states that "the BLM only requires that mining claims be identified down to the affected quarter section(s)." Because a case is mapped to every affected quarter section, one mining claim can fall in two sections or townships. A count should say whether such a case is counted once or in each unit it touches.
The metadata also scores mapping quality. Some cases are "mapped to the Section," some "map to the County," and some have "only attributes" and no geometry. Those cases fall out of an area count unless they are added from the case list.
Counts versus acreage
Mining claims differ in size. A lode claim is limited to 1,500 by 600 feet; an individual placer claim to 20 acres; an association placer claim to 160 acres (43 CFR 3832.22). A count treats each the same. The "Case Acres" field in BLM's data allows density to be expressed as claimed acres per unit area as well.
Density over time
Comparing counts across dates shows change. Because a new mining claim must be filed with BLM "by the 90th day after the date of location" (43 CFR 3833.11(a)), the most recent 90 days of staking may not yet appear. The annual maintenance fee is due on or before September 1, and a mining claim is forfeited if it is not paid (43 CFR 3830.91(a)(3)), so compare counts taken at the same point in the fee year.
What density cannot show
Density measures recorded interest, not mineral value. Recording a mining claim "does not make a claim or site valid if it not otherwise valid under applicable law" (43 CFR 3833.1(b)). A crowded township may reflect one holder's large block rather than broad interest, so density is best read alongside who holds the mining claims.
Why it matters in mining claim research
Density maps point to where to look closer, whether for open ground, competing holders, or conflicts. The answers still come from the case records. See also Claims Intelligence, Prospectivity, Claim Block, and Area of Interest.
Related Terms
Mining Claim
A parcel of federal land on which a claimant asserts the right to possess and develop a valuable mineral deposit under the Mining Law of 1872.
Area of Interest
The boundary drawn around the ground being researched, such as a list of townships and sections or a mapped polygon, that sets which records are pulled.
Prospectivity
How likely an area is to contain a mineral deposit of a particular type, judged from its geology and the deposits already known nearby.
MRDS
The Mineral Resources Data System, a USGS database of reports on mines, prospects, and mineral occurrences, most complete for the United States, no longer systematically updated.
Claims Research
Finding and reading the records of the mining claims on a tract, from BLM and the county, to learn what is claimed, by whom, and whether the filings were made on time.
Claims Intelligence
Tracking BLM mining claim records over time to see who holds ground in an area, how their positions change, and what those changes suggest.