# Methodology: Walgreen Co. NPI records

**Source:** CMS NPPES Data Dissemination V.2, full replacement monthly file for September 2026 (CMS label "September 14, 2026"; records through 2026-09-13).
File `NPPES_Data_Dissemination_September_2026_V2.zip`, sha256 `6573e0d148c18a9a9d974248d77447744bd9666aa288c38d13ebf3d766e3cec4`, from <https://download.cms.gov/nppes/NPPES_Data_Dissemination_September_2026_V2.zip>. The three weekly update files dated 7-27 Sep 2026 feed the change log (checksums in provenance.json).

**Scope:** active NPI-2 records whose legal business name, upper-cased with punctuation removed, equals "WALGREEN CO" (11,124 records, listed with 29 different authorized officials). Deactivated NPIs are excluded; NPPES blanks their names, so they cannot be attributed to an organization. The literal NPPES placeholder `<UNAVAIL>` is treated as empty.

**Locations:** distinct pairs of normalized first address line and five-digit ZIP across primary and secondary practice addresses (10,392). In the CSV, `location_key` is the record's primary pair and `secondary_practice_addresses` lists its secondary pairs (`;`-joined `address|ZIP`, same normalization: upper-cased, whitespace collapsed), with `secondary_practice_states` giving each secondary location's state in the same order; the distinct union of both columns gives the location count, and a state's count uses the secondary pairs located in that state. A practice address can carry more than one NPI-2 record: 726 primary addresses have two or more records (1,470 records in all).

**Taxonomy:** NUCC Health Care Provider Taxonomy code set 26.1. Primary taxonomy is the code flagged primary on the record (code 1 if none is flagged).

**Last-update age:** years from each record's NPPES last-update date to 2026-10-01; "last NPPES update 5+ years ago" (CSV `not_updated_5y`) means a last-update date before 2021-10-01. The date shows when the record was last changed in NPPES, not whether its address or phone number is still correct. National comparison: 1,159,329 of 1,972,058 active NPI-2 records in the same September 2026 file.

**Selection:** legal business names on active NPI-2 records (1,444,908) ranked by practice-location rows; this name ranks first. The rank counts legal names, not corporate families.

**State pages:** Florida; a state page is indexed when it has at least 5 street-addressed records. Counties and metro areas come from the Census 2020 ZIP Code Tabulation Area to county relationship file and the 2023 CBSA delineation file, applied to each record's ZIP code (state CSV columns `county` and `cbsa`).

**Other names:** NPPES lets each record list other names the organization uses or has used, such as a store or department name. The JSON field `other_name_counts` lists the most frequent names as filed, with entry counts; NPPES does not say why a name was added.

**Owner and review:** Owner: Rome (Provyx). Review trigger: each monthly NPPES full file (next: October 2026 release), or a correction report; figures are re-derived from the new file.

**License:** CC BY 4.0 for derived fields; the underlying NPPES data is public.