An APN, or Assessor's Parcel Number (also called a parcel number or PIN), is the unique identifier a county assessor assigns to a specific piece of land for tax purposes. Every parcel in a county has one. It is the stable key that ties together the deeds, assessments, permits, and ownership records for that property.
Street addresses are messy: they get abbreviated, misspelled, and reused. The APN does not. Because it is assigned per parcel and rarely changes, it is the most reliable way to gather everything on file at a property: who owns it, what it is assessed at, what has been built on it, and what has been recorded against it. It is the spine that property data hangs on.
APNs are unique within a county, not nationally, and every county formats them differently (with dashes, dots, or leading zeros). A parcel number alone is ambiguous without its county. Joining property records reliably means normalizing these formats and keying on the parcel plus its jurisdiction, so the same parcel is never split or two parcels merged.
Related on Amalgament: Property records API · Building permits API
No. An address describes a location for mail; an APN identifies a legal parcel for the assessor. One parcel can cover several addresses, and one address can span multiple parcels, so the APN is the more precise key.
Yes. With a parcel spine that normalizes county formats, an APN (plus its county and state) resolves to every record joined to that parcel, from deeds to permits to the owning entity.
More terms: KYB (Know Your Business) · UCC filing (UCC-1) · MCP server · Entity resolution · Business registry (Secretary of State filing) · UEI and SAM.gov · Non-FCRA (business-purpose) data · Context layer (for AI)