# County expansion selection

Retrieved 2026-10-15. CMS Medicare Monthly Enrollment's latest available data month is June 2026; catalog publication/modification date is 2026-09-23. This does not mean all CMS enrollment products stop in June: separate CMS contract enrollment releases already reach October 2026. The unified monthly enrollment report is used here because it directly publishes county total Part D, standalone PDP and MA-PD counts consistently.

- Dataset: https://data.cms.gov/summary-statistics-on-beneficiary-enrollment/medicare-and-medicaid-reports/medicare-monthly-enrollment
- Live catalog: https://data.cms.gov/data.json
- Exact downloaded CSV: https://data.cms.gov/sites/default/files/2026-09/4f178691-06d8-4a77-96ea-43fa911e28b5/Medicare%20Monthly%20Enrollment%20Data_June%202026.csv
- Methodology: https://data.cms.gov/resources/medicare-monthly-enrollment-methodology
- Data dictionary: https://data.cms.gov/resources/medicare-monthly-enrollment-data-dictionary
- Data dictionary PDF: https://data.cms.gov/sites/default/files/2025-12/Medicare%20Monthly%20Enrollment%20Data%20Dictionary.pdf

Filter YEAR=2026, MONTH=June and BENE_GEO_LVL=County. Rank numeric PRSCRPTN_DRUG_TOT_BENES descending. Select the highest-ranked county in each previously unrepresented state; California is represented by the existing Los Angeles guide. Stop at eight additional states/counties. This gives all eight counties within the top 16 nationally and adds the Pacific Northwest, Southwest, Midwest, South and Northeast. It is a geographic expansion selection, not the unqualified eight largest counties.

Use PRSCRPTN_DRUG_TOT_BENES as Part D enrollment and preserve PRSCRPTN_DRUG_MAPD_BENES and PRSCRPTN_DRUG_PDP_BENES separately. All eight selected rows satisfy total = MA-PD + PDP exactly. Counts are enrolled beneficiaries, not observed prescription use, fills or spending; they are June 2026 counts, not projections of 2027 enrollment. The 2027 county guides cover general-enrollment MA-PD landscape plans only, so the selection denominator includes beneficiaries beyond that guide's plan scope.

County names were matched exactly to the September 2026 CMS landscape. The 2027 general-enrollment MA-PD counts in the selection files come from that separate plan landscape, not from June enrollment totals. No suppressed enrollment count is estimated.


`selection.json` and `selection.csv` preserve the selected county counts, national ranks, exact source URLs and source dates. The original source CSV SHA-256 is `2b99b85e56448a2441e5ee88f301da9928a8410ad5be7d5957590720a2f542c1`.