What does this Medicare market look like beyond enrollment?
Today this page carries the aggregate market context that is already ingested: size, MA & other health plan share, dual population, dual density and full-dual share, county by county. The demographic layer that would make it a real audience view, age mix, income, language, broadband and rurality, comes from Census ACS county tables that this site has not ingested. It is listed below with the exact source rather than approximated.
Available now: aggregate market context
The fifteen largest-Medicare counties by dual density, as an illustration of the shape of the data. The full 3,199-county set drives the opportunity ranking and can be filtered there.
| County | Medicare | MA & other health plan share | Duals | Dual density | Full-dual share |
|---|---|---|---|---|---|
| Bronx County, NY | 232,893 | 71.2% | 133,031 | 57.1% | 93.6% |
| Kings County, NY | 412,291 | 57.5% | 206,695 | 50.1% | 92.7% |
| Suffolk County, MA | 114,786 | 42.3% | 50,062 | 43.6% | 83.0% |
| Miami-Dade County, FL | 522,929 | 75.4% | 227,397 | 43.5% | 59.7% |
| Queens County, NY | 421,274 | 60.9% | 183,027 | 43.4% | 89.0% |
| New York County, NY | 299,215 | 47.3% | 115,145 | 38.5% | 93.1% |
| Philadelphia County, PA | 266,209 | 60.4% | 101,889 | 38.3% | 88.7% |
| Tulare County, CA | 70,870 | 37.3% | 26,131 | 36.9% | 99.5% |
| Hidalgo County, TX | 125,198 | 77.2% | 45,916 | 36.7% | 52.7% |
| District Of Columbia, DC | 97,554 | 34.5% | 34,310 | 35.2% | 64.6% |
| San Francisco County, CA | 159,389 | 51.3% | 55,648 | 34.9% | 99.8% |
| Hampden County, MA | 110,033 | 45.5% | 37,998 | 34.5% | 82.0% |
| Cameron County, TX | 73,258 | 74.3% | 24,763 | 33.8% | 49.5% |
| Kern County, CA | 135,029 | 47.4% | 43,792 | 32.4% | 99.5% |
| Los Angeles County, CA | 1,707,013 | 57.3% | 543,709 | 31.9% | 99.3% |
Counties with at least 50,000 Medicare beneficiaries, ranked by dual density. April 2026 CMS county file.
Planned: the public sources that would deepen this
| Layer | Planned public source | What it would change |
|---|---|---|
| Age 65+ population and age mix | Census ACS 5-year, county tables | Separates an ageing-in market from a switching market more directly than Medicare counts alone. |
| Income and poverty | Census ACS 5-year, county tables | Context for dual and LIS likelihood at market level, and for channel affordability assumptions. |
| Language spoken at home and English proficiency | Census ACS 5-year, county tables | Drives translation requirements and channel selection. Aggregate only, never applied to a person. |
| Broadband and device access | Census ACS 5-year, county tables | Decides how much of a plan can realistically be digital in a given county. |
| Rural and urban classification | Census / OMB delineation files | Rural markets need different reach assumptions and different provider-access messaging. |
| Aggregate disability indicators | Census ACS 5-year, county tables | Market-level context only. Never used to build an audience segment. |
Coming next Each of these is a county-level aggregate table from a named public source. None of them is a person-level file, and none would be used to build one.
So what / Now what Interpretation
Dual density and full-dual share are already enough to change a channel plan. A county where a quarter of Medicare beneficiaries are dual-eligible needs community, provider and trusted-intermediary channels and a year-round calendar. A low-dual, high-health-plan-share county is a mass-reach switching market where the same budget behaves completely differently. That distinction is available today; the demographic layer would sharpen it, not create it.
- Use dual density and full-dual share as the first channel-planning cut, before any demographic overlay exists.
- Pair this with the D-SNP view: county dual density plus state capture tells you whether the duals in the county are already enrolled somewhere.
- When the ACS layer lands, treat language and broadband as production and channel constraints, not as audience segments.
- Keep the aggregate-only line in your own briefs. It is a defensible position with regulators and a sound one with members.
Sources and vintage
| Dataset | Source | Vintage | Status |
|---|---|---|---|
| MA and other health plan enrollment and share by county | CMS Medicare Monthly Enrollment (BENE_GEO_LVL=County) | April 2026 | live |
| Dual-eligible counts by county | CMS Medicare Monthly Enrollment (DUAL_TOT_BENES / FULL_DUAL_TOT_BENES) | April 2026 | live |
| SNP enrollment, integration and plans | CMS SNP Comprehensive Report (SNP_REPORT_PART_17) | August 2026 | live |
| Marketing Opportunity Score | Derived, tools/build_marketing_data.py v0.1 | 2026-08-26 | modeled |
Full methodology: Marketing Opportunity Score · site methodology.