BLM Serial Number

A BLM serial number is the case number BLM gives each mining claim or site it records. "The BLM will assign a serial number to each claim or site that is received with the full processing, location, and maintenance fee until the funds run out" (43 CFR 3830.95(b)). A mining claim filed without full fees is not recorded and gets no number.

Where serial numbers come from

BLM's Glossary of Surveying and Mapping Terms (1980) says "Serial registers were instituted in 1908 as a digest of land case records," with each case "identified by the serial number assigned to it."

MLRS serial numbers

BLM's MLRS help center says it "created a new serial number for all existing and new cases to simplify the written serial number," because the previous number "was overly complicated and prone to errors." For mining claims, the MLRS number has "the two-character postal code for the admin state." In BLM's published mining claim data these take the form of two letters and nine digits, for example NV101656950 or AZ101424500. For existing mining claims, "MLRS serial numbers are assigned in the order that the cases are migrated from LR2000," and "Active mining claims are migrated before mining claims in other statuses."

Legacy LR2000 numbers

BLM describes the LR2000 format as a "Two-character geographic state," a "One-to-four-character land office," an optional zero prefix for old cases, a "Six-digit serial number," and an optional suffix. BLM's data carries both numbers: NV101656950 has the legacy number NMC1000000, and AZ101424500 has AMC100784. Legacy numbers remain searchable in MLRS, and BLM reports "display columns for the new MLRS Serial Number and Legacy Serial Number."

Where the serial number must appear

• Fee payments, listed "by claim name, and by the BLM serial number if BLM has notified you what the serial numbers are" (43 CFR 3834.12)
• Transfer notices, with "the serial number BLM assigned to the claim or site when the notice or certificate of location was originally recorded" (43 CFR 3833.32(b)(1))
• Affidavits of assessment work and notices of intent to hold, "if available" (43 CFR 3835.32, 3835.33)
• Notices and plans of operations, which must give "the BLM serial number(s) of any unpatented mining claim(s) where the disturbance would occur" (43 CFR 3809.301(b)(1), 3809.401(b)(1))

Why it matters in mining claim research

The serial number ties together the recording, every fee payment, every transfer, and every decision on a mining claim. Older county documents, title opinions, and correspondence cite legacy numbers, so research matches each legacy number to its MLRS number before comparing records. A county-recorded mining claim with no BLM serial number is a sign it was never recorded with BLM.