About this index & how it's been checked
The Aging Vulnerability Index (AVI) is this platform's own construction, modeled on the CDC/ATSDR Social Vulnerability Index methodology but not a CDC product and not independently validated. It combines Census ACS data on the population 65 and older — demographic aging pressure, economic precarity, health/disability/isolation, and housing/transportation burden — into a single percentile ranking of U.S. counties. The underlying inputs are official Census data; the index construction and weighting are this platform's own.
Reference-county check
A face-validity check against real counties with well-documented age profiles — the same method used to calibrate this platform's seasonal-community threshold. Higher percentile = more aging-vulnerable.
- ✓ Sumter County, FL — 79.8th percentile (expected HIGH, The Villages — often cited as the oldest-median-age U.S. county)
- ✓ Charlotte County, FL — 90.8th percentile (expected HIGH, Retirement destination)
- ✓ Citrus County, FL — 88.1th percentile (expected HIGH, Retirement destination)
- ✓ Highlands County, FL — 95.9th percentile (expected HIGH, Retirement destination)
- ✓ Brazos County, TX — 17.0th percentile (expected LOW, Texas A&M)
- ✓ Story County, IA — 8.9th percentile (expected LOW, Iowa State)
- ✓ Whitman County, WA — 10.3th percentile (expected LOW, Washington State University)
- ✓ Tompkins County, NY — 7.6th percentile (expected LOW, Cornell)
Highest / lowest AVI by county population
Under 50,000
Highest
- Catron County, NM — 100.0th pctile (pop. 3,743)
- De Baca County, NM — 99.9th pctile (pop. 1,576)
- Ozark County, MO — 99.8th pctile (pop. 8,873)
- Scott County, VA — 99.6th pctile (pop. 21,479)
- Harney County, OR — 99.6th pctile (pop. 7,499)
Lowest
- Martin County, TX — 0.0th pctile (pop. 5,218)
- Jim Hogg County, TX — 0.1th pctile (pop. 4,727)
- Haskell County, KS — 0.1th pctile (pop. 3,641)
- Hanson County, SD — 0.1th pctile (pop. 3,472)
- Trousdale County, TN — 0.2th pctile (pop. 11,957)
50,000-99,999
Highest
- Nye County, NV — 96.7th pctile (pop. 54,344)
- Gila County, AZ — 96.7th pctile (pop. 53,795)
- Raleigh County, WV — 96.0th pctile (pop. 73,195)
- Wilkes County, NC — 95.6th pctile (pop. 65,935)
- Pittsylvania County, VA — 94.0th pctile (pop. 59,856)
Lowest
- Oldham County, KY — 0.0th pctile (pop. 69,257)
- Eagle County, CO — 0.2th pctile (pop. 55,135)
- Lincoln County, SD — 0.5th pctile (pop. 70,638)
- Johnson County, MO — 0.9th pctile (pop. 54,732)
- Lafayette County, MS — 1.3th pctile (pop. 58,327)
100,000-299,999
Highest
- Highlands County, FL — 95.9th pctile (pop. 105,702)
- Mohave County, AZ — 93.9th pctile (pop. 220,517)
- Douglas County, OR — 93.0th pctile (pop. 112,072)
- Charlotte County, FL — 90.8th pctile (pop. 201,064)
- Indian River County, FL — 90.3th pctile (pop. 166,936)
Lowest
- Union County, NC — 0.8th pctile (pop. 250,958)
- Scott County, MN — 1.1th pctile (pop. 154,557)
- Williamson County, TN — 1.2th pctile (pop. 260,351)
- St. Mary's County, MD — 1.3th pctile (pop. 115,126)
- Dallas County, IA — 1.5th pctile (pop. 107,968)
300,000 and higher
Highest
- Pinellas County, FL — 90.1th pctile (pop. 963,481)
- Collier County, FL — 89.9th pctile (pop. 398,291)
- Marion County, FL — 87.1th pctile (pop. 400,078)
- Lee County, FL — 86.1th pctile (pop. 817,666)
- Palm Beach County, FL — 85.0th pctile (pop. 1,533,806)
Lowest
- Hamilton County, IN — 0.6th pctile (pop. 365,056)
- Prince William Count, VA — 2.1th pctile (pop. 488,880)
- Davis County, UT — 2.1th pctile (pop. 370,924)
- Douglas County, CO — 2.2th pctile (pop. 377,150)
- Loudoun County, VA — 2.4th pctile (pop. 432,998)
Hamilton County — Aging Vulnerability Index by census tract
Candidate index, not validated against ground truth — 2020–2024 ACS 5-year
Hamilton County — Aging Vulnerability Index by census tract
Where this is
Shading: Aging Vulnerability Index
Lower (0 to 5)Lower-middle (7 to 11)Middle (11 to 29)Upper-middle (30 to 47)Higher (49 to 89)
Each unit is shaded by its Aging Vulnerability Index value and grouped into equal-count bands (quantiles) against the other units shown — lighter = lower, darker = higher. It ranks position among the units in view; it does not grade places, and the ranges shift with which units are shown.
The map is bounded to this parent geography — it shows the selected unit among its own siblings only, the same depth rule the drill-down uses. Shading ranks position on the measure among the units shown; it does not grade places.
The panel shows the county overview. Click a tract for its own percentile and theme scores — the county overview stays visible alongside it for comparison.
Median tract: 20th percentile (among all U.S. tracts).
These tracts span the 0th percentile to the 89th percentile. The width of that range is the internal disparity.
Widest spread across these tracts: Housing & Transportation, 65+ — this theme most separates the higher- and lower-ranked tracts here.
AVI ranks each tract's position relative to a comparison set; it is not averaged into one number for the area, because percentiles do not average meaningfully. The distribution — median, range, and shape below — is the summary.
Well above the median — 4 tracts (80th–100th percentile)
Tract 1108.16 — 89th percentile — Well above the median 4 of 12 flagged
Driven by Demographic Aging Pressure (above), Health, Disability & Isolation ‡ (well above) and Social Isolation (well above); near the median on Housing & Transportation, 65+ ‡; below the median on Economic Precarity, 65+ ‡.
‡ theme includes at least one flagged input.
Tract 1109.05 — 86th percentile — Well above the median 7 of 12 flagged
Driven by Economic Precarity, 65+ ‡ (well above), Health, Disability & Isolation ‡ (above), Housing & Transportation, 65+ ‡ (well above) and Social Isolation ‡ (above); near the median on Demographic Aging Pressure ‡.
‡ theme includes at least one flagged input.
Tract 1110.11 — 84th percentile — Well above the median 5 of 12 flagged
Driven by Demographic Aging Pressure (above), Housing & Transportation, 65+ ‡ (above) and Social Isolation ‡ (well above); near the median on Economic Precarity, 65+ ‡ and Health, Disability & Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1108.11 — 84th percentile — Well above the median 7 of 12 flagged
Driven by Demographic Aging Pressure ‡ (above), Health, Disability & Isolation ‡ (well above) and Housing & Transportation, 65+ ‡ (above); near the median on Social Isolation ‡; below the median on Economic Precarity, 65+ ‡.
‡ theme includes at least one flagged input.
Above the median — 5 tracts (60th–80th percentile)
Tract 1110.06 — 76th percentile — Above the median 7 of 12 flagged
Driven by Demographic Aging Pressure (above), Health, Disability & Isolation ‡ (well above) and Housing & Transportation, 65+ ‡ (above); below the median on Economic Precarity, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1104.01 — 71st percentile — Above the median 5 of 12 flagged
Driven by Demographic Aging Pressure (above), Economic Precarity, 65+ ‡ (well above), Housing & Transportation, 65+ ‡ (well above) and Social Isolation ‡ (above); below the median on Health, Disability & Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1105.18 — 68th percentile — Above the median 5 of 12 flagged
Driven by Demographic Aging Pressure (well above) and Housing & Transportation, 65+ ‡ (above); near the median on Economic Precarity, 65+ ‡ and Social Isolation ‡; below the median on Health, Disability & Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1108.10 — 65th percentile — Above the median 7 of 12 flagged
Driven by Economic Precarity, 65+ ‡ (above) and Housing & Transportation, 65+ ‡ (well above); near the median on Demographic Aging Pressure ‡, Health, Disability & Isolation ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1110.03 — 61st percentile — Above the median 4 of 12 flagged
Driven by Demographic Aging Pressure (well above) and Health, Disability & Isolation ‡ (above); below the median on Economic Precarity, 65+, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Near the median — 4 tracts (40th–60th percentile)
Tract 1111.04 — 53rd percentile — Near the median 8 of 12 flagged
Driven by Demographic Aging Pressure ‡ (well above); near the median on Health, Disability & Isolation ‡ and Housing & Transportation, 65+ ‡; below the median on Economic Precarity, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1109.06 — 50th percentile — Near the median 8 of 12 flagged
Driven by Health, Disability & Isolation ‡ (well above) and Housing & Transportation, 65+ ‡ (well above); below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1101.02 — 49th percentile — Near the median 7 of 12 flagged
Driven by Housing & Transportation, 65+ ‡ (above); near the median on Demographic Aging Pressure ‡, Health, Disability & Isolation ‡ and Social Isolation ‡; below the median on Economic Precarity, 65+ ‡.
‡ theme includes at least one flagged input.
Tract 1107.00 — 47th percentile — Near the median 7 of 12 flagged
Driven by Health, Disability & Isolation ‡ (above) and Social Isolation ‡ (above); near the median on Economic Precarity, 65+ ‡; below the median on Demographic Aging Pressure ‡ and Housing & Transportation, 65+ ‡.
‡ theme includes at least one flagged input.
Below the median — 17 tracts (20th–40th percentile)
Tract 1109.12 — 40th percentile — Below the median 5 of 12 flagged
Driven by Demographic Aging Pressure ‡ (well above); near the median on Housing & Transportation, 65+ ‡; below the median on Economic Precarity, 65+ ‡, Health, Disability & Isolation and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1103.02 — 39th percentile — Below the median 5 of 12 flagged
Driven by Health, Disability & Isolation ‡ (above); near the median on Housing & Transportation, 65+ ‡ and Social Isolation ‡; below the median on Demographic Aging Pressure ‡ and Economic Precarity, 65+ ‡.
‡ theme includes at least one flagged input.
Tract 1108.15 — 38th percentile — Below the median 8 of 12 flagged
Driven by Housing & Transportation, 65+ ‡ (well above) and Social Isolation ‡ (above); near the median on Health, Disability & Isolation ‡; below the median on Demographic Aging Pressure ‡ and Economic Precarity, 65+ ‡.
‡ theme includes at least one flagged input.
Tract 1108.14 — 36th percentile — Below the median 7 of 12 flagged
Driven by Health, Disability & Isolation ‡ (well above); near the median on Demographic Aging Pressure ‡; below the median on Economic Precarity, 65+ ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1110.07 — 36th percentile — Below the median 3 of 12 flagged
Driven by Economic Precarity, 65+ ‡ (above) and Social Isolation ‡ (above); near the median on Demographic Aging Pressure; below the median on Health, Disability & Isolation ‡ and Housing & Transportation, 65+.
‡ theme includes at least one flagged input.
Tract 1105.13 — 32nd percentile — Below the median 7 of 12 flagged
Driven by Health, Disability & Isolation ‡ (above); near the median on Housing & Transportation, 65+ ‡; below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1105.09 — 32nd percentile — Below the median 6 of 12 flagged
Driven by Housing & Transportation, 65+ ‡ (above); near the median on Demographic Aging Pressure ‡ and Social Isolation ‡; below the median on Economic Precarity, 65+ ‡ and Health, Disability & Isolation.
‡ theme includes at least one flagged input.
Tract 1108.20 — 32nd percentile — Below the median 6 of 12 flagged
Driven by Economic Precarity, 65+ ‡ (above); near the median on Demographic Aging Pressure ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡; below the median on Health, Disability & Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1108.12 — 31st percentile — Below the median 8 of 12 flagged
Driven by Housing & Transportation, 65+ ‡ (above); near the median on Economic Precarity, 65+ ‡ and Health, Disability & Isolation ‡; below the median on Demographic Aging Pressure ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1104.04 — 30th percentile — Below the median 6 of 12 flagged
Driven by Health, Disability & Isolation ‡ (above); below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1103.03 — 29th percentile — Below the median 6 of 12 flagged
Near the median on Demographic Aging Pressure ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡; below the median on Economic Precarity, 65+ ‡ and Health, Disability & Isolation.
‡ theme includes at least one flagged input.
Tract 1106.00 — 25th percentile — Below the median 5 of 12 flagged
Driven by Housing & Transportation, 65+ ‡ (well above); near the median on Social Isolation ‡; below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡ and Health, Disability & Isolation.
‡ theme includes at least one flagged input.
Tract 1110.04 — 22nd percentile — Below the median 5 of 12 flagged
Driven by Demographic Aging Pressure ‡ (above); below the median on Economic Precarity, 65+, Health, Disability & Isolation ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1102.02 — 22nd percentile — Below the median 6 of 12 flagged
Below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1111.01 — 21st percentile — Below the median 6 of 12 flagged
Driven by Health, Disability & Isolation ‡ (above); below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1105.14 — 20th percentile — Below the median 5 of 12 flagged
Near the median on Demographic Aging Pressure ‡; below the median on Economic Precarity, 65+, Health, Disability & Isolation ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1105.16 — 20th percentile — Below the median 6 of 12 flagged
Driven by Housing & Transportation, 65+ ‡ (well above); below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Well below the median — 27 tracts (0th–20th percentile)
Tract 1102.01 — 15th percentile — Well below the median 7 of 12 flagged
Near the median on Housing & Transportation, 65+ ‡; below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1103.01 — 13th percentile — Well below the median 7 of 12 flagged
Near the median on Housing & Transportation, 65+ ‡; below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1111.03 — 12th percentile — Well below the median 3 of 12 flagged
Driven by Health, Disability & Isolation ‡ (above); below the median on Demographic Aging Pressure, Economic Precarity, 65+ ‡, Housing & Transportation, 65+ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1105.11 — 11th percentile — Well below the median 4 of 12 flagged
Near the median on Health, Disability & Isolation ‡; below the median on Demographic Aging Pressure, Economic Precarity, 65+ ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1108.19 — 11th percentile — Well below the median 7 of 12 flagged
Driven by Health, Disability & Isolation ‡ (above) and Housing & Transportation, 65+ ‡ (above); below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1109.11 — 11th percentile — Well below the median 7 of 12 flagged
Driven by Health, Disability & Isolation ‡ (well above); below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1110.12 — 10th percentile — Well below the median 5 of 12 flagged
Near the median on Economic Precarity, 65+ ‡ and Social Isolation ‡; below the median on Demographic Aging Pressure ‡, Health, Disability & Isolation and Housing & Transportation, 65+ ‡.
‡ theme includes at least one flagged input.
Tract 1108.05 — 10th percentile — Well below the median 5 of 12 flagged
Near the median on Demographic Aging Pressure ‡; below the median on Economic Precarity, 65+ ‡, Health, Disability & Isolation, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1104.06 — 10th percentile — Well below the median 5 of 12 flagged
Near the median on Economic Precarity, 65+ ‡ and Housing & Transportation, 65+ ‡; below the median on Demographic Aging Pressure ‡, Health, Disability & Isolation and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1105.17 — 9th percentile — Well below the median 5 of 12 flagged
Below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1105.05 — 9th percentile — Well below the median 6 of 12 flagged
Driven by Housing & Transportation, 65+ ‡ (above); below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1109.07 — 8th percentile — Well below the median 5 of 12 flagged
Near the median on Demographic Aging Pressure ‡; below the median on Economic Precarity, 65+ ‡, Health, Disability & Isolation, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1109.09 — 7th percentile — Well below the median 5 of 12 flagged
Driven by Health, Disability & Isolation ‡ (above); below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1105.12 — 7th percentile — Well below the median 5 of 12 flagged
Below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1110.10 — 7th percentile — Well below the median 6 of 12 flagged
Near the median on Economic Precarity, 65+ ‡; below the median on Demographic Aging Pressure ‡, Health, Disability & Isolation, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1108.22 — 7th percentile — Well below the median 5 of 12 flagged
Driven by Health, Disability & Isolation ‡ (above); near the median on Economic Precarity, 65+ ‡; below the median on Demographic Aging Pressure ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1108.17 — 5th percentile — Well below the median 6 of 12 flagged
Below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1105.15 — 5th percentile — Well below the median 6 of 12 flagged
Below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1108.18 — 5th percentile — Well below the median 6 of 12 flagged
Below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+, Health, Disability & Isolation ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1101.01 — 5th percentile — Well below the median 5 of 12 flagged
Near the median on Economic Precarity, 65+ ‡ and Housing & Transportation, 65+ ‡; below the median on Demographic Aging Pressure ‡, Health, Disability & Isolation and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1104.05 — 4th percentile — Well below the median 6 of 12 flagged
Near the median on Economic Precarity, 65+ ‡ and Housing & Transportation, 65+ ‡; below the median on Demographic Aging Pressure ‡, Health, Disability & Isolation and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1109.04 — 4th percentile — Well below the median 6 of 12 flagged
Near the median on Health, Disability & Isolation ‡; below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1108.07 — 2nd percentile — Well below the median 4 of 12 flagged
Below the median on Demographic Aging Pressure, Economic Precarity, 65+ ‡, Health, Disability & Isolation, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1109.10 — 2nd percentile — Well below the median 7 of 12 flagged
Driven by Health, Disability & Isolation ‡ (above); below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1108.13 — 1st percentile — Well below the median 6 of 12 flagged
Near the median on Health, Disability & Isolation ‡; below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1110.09 — 1st percentile — Well below the median 5 of 12 flagged
Below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation, Housing & Transportation, 65+ ‡ and Social Isolation ‡.
‡ theme includes at least one flagged input.
Tract 1108.21 — 0th percentile — Well below the median 4 of 12 flagged
Below the median on Demographic Aging Pressure ‡, Economic Precarity, 65+ ‡, Health, Disability & Isolation, Housing & Transportation, 65+ and Social Isolation ‡.
‡ theme includes at least one flagged input.
AVI = a candidate Aging Vulnerability Index, computed by this platform from American Community Survey 2020–2024 5-year estimates, following the same method shape (percentile rank -> theme sum -> re-rank -> overall) as the CDC/ATSDR SVI this platform also recomputes — but AVI itself has no published ground truth to validate against. It is a first-cut, directional design. Percentiles rank each tract against all U.S. tracts.
Several of AVI's 12 input signals carry a documented high margin of error at this grain (most notably lack of health insurance, 65+) and are kept in the index with a flag rather than dropped, to preserve variable coverage. A tract's flag count (shown per-tract above) is a direct measure of how much its rank should be read as directional rather than precise.