We combined Census heating and housing-age data with 30 years of NOAA climate records to rank all 48 states with complete data - and flagged the three without it rather than fudging. Arizona leads at 74.4.
See the full rankingMethodologyIndex 0-100. Higher = more structural reasons for duct attention: more homes with ducts, longer cooling seasons, drier air, older housing. It is a demand-conditions index, not a claim about any individual home.
| # | State | Index | Duct-likely heat (ACS) | Cooling degree days (NOAA) | Median home age |
|---|---|---|---|---|---|
| 1 | Arizona | 74.4 | 93.2% | 3,137 | 34 yrs |
| 2 | Nevada | 68.2 | 93.6% | 2,232 | 30 yrs |
| 3 | Florida | 64.2 | 96.0% | 3,658 | 38 yrs |
| 4 | Texas | 62.0 | 95.8% | 2,921 | 36 yrs |
| 5 | Louisiana | 61.0 | 96.8% | 2,779 | 44 yrs |
| 6 | Kansas | 56.8 | 89.9% | 1,508 | 51 yrs |
| 7 | Oklahoma | 56.5 | 91.2% | 1,990 | 46 yrs |
| 8 | New Mexico | 56.2 | 84.8% | 1,063 | 42 yrs |
| 9 | Nebraska | 55.5 | 90.6% | 1,043 | 51 yrs |
| 10 | California | 55.3 | 90.6% | 971 | 50 yrs |
| 11 | Illinois | 54.4 | 93.8% | 913 | 56 yrs |
| 12 | Utah | 53.9 | 95.5% | 577 | 35 yrs |
| 13 | Alabama | 52.2 | 93.0% | 1,994 | 41 yrs |
| 14 | Ohio | 51.7 | 89.7% | 815 | 56 yrs |
| 15 | New Jersey | 51.6 | 88.9% | 895 | 57 yrs |
| 16 | Mississippi | 51.2 | 88.0% | 2,254 | 40 yrs |
| 17 | South Carolina | 50.3 | 94.4% | 1,971 | 35 yrs |
| 18 | Iowa | 50.2 | 84.5% | 842 | 55 yrs |
| 19 | Missouri | 50.0 | 87.8% | 1,306 | 48 yrs |
| 20 | New York | 49.3 | 73.7% | 647 | 68 yrs |
| 21 | Michigan | 49.1 | 86.8% | 606 | 54 yrs |
| 22 | Wyoming | 49.1 | 82.8% | 304 | 46 yrs |
| 23 | Indiana | 49.0 | 89.6% | 932 | 50 yrs |
| 24 | Arkansas | 48.9 | 90.0% | 1,819 | 39 yrs |
| 25 | Georgia | 48.5 | 94.2% | 1,763 | 35 yrs |
| 26 | Tennessee | 48.3 | 94.1% | 1,451 | 40 yrs |
| 27 | Colorado | 48.2 | 92.0% | 354 | 39 yrs |
| 28 | Maryland | 47.7 | 86.7% | 1,167 | 47 yrs |
| 29 | South Dakota | 47.7 | 79.8% | 730 | 47 yrs |
| 30 | Kentucky | 47.6 | 90.0% | 1,256 | 44 yrs |
| 31 | Pennsylvania | 47.1 | 76.1% | 729 | 61 yrs |
| 32 | North Dakota | 46.9 | 81.4% | 478 | 45 yrs |
| 33 | West Virginia | 46.3 | 86.2% | 819 | 50 yrs |
| 34 | Virginia | 46.1 | 89.6% | 1,154 | 42 yrs |
| 35 | Minnesota | 45.4 | 84.2% | 486 | 48 yrs |
| 36 | Wisconsin | 45.0 | 82.3% | 535 | 51 yrs |
| 37 | North Carolina | 44.9 | 89.4% | 1,494 | 36 yrs |
| 38 | Oregon | 44.4 | 90.3% | 260 | 46 yrs |
| 39 | Montana | 43.9 | 77.6% | 220 | 46 yrs |
| 40 | Massachusetts | 43.5 | 69.6% | 547 | 63 yrs |
| 41 | Rhode Island | 43.0 | 65.5% | 590 | 65 yrs |
| 42 | Idaho | 42.1 | 86.4% | 533 | 36 yrs |
| 43 | Delaware | 40.6 | 79.3% | 1,170 | 40 yrs |
| 44 | Washington | 40.3 | 91.2% | 203 | 42 yrs |
| 45 | Connecticut | 35.2 | 54.2% | 632 | 59 yrs |
| 46 | New Hampshire | 17.3 | 31.9% | 322 | 48 yrs |
| 47 | Vermont | 15.3 | 25.9% | 243 | 50 yrs |
| 48 | Maine | 12.0 | 18.2% | 254 | 50 yrs |
| — | Alaska | Unranked - no complete NOAA statewide climate series - listed unranked rather than reweighted | |||
| — | District of Columbia | Unranked - no complete NOAA statewide climate series - listed unranked rather than reweighted | |||
| — | Hawaii | Unranked - no complete NOAA statewide climate series - listed unranked rather than reweighted | |||
Download the data: CSV · JSON — CC BY 4.0, attribution "DuctDove Duct Attention Index 2026".
Arizona tops the index at 74.4: 93.2% of homes heat with duct-likely gas or electric warm-air systems (functionally, nearly every house has ducts), a 3,137 cooling-degree-day season that runs those ducts most of the year, and desert dust that finds every unsealed joint. Nevada (68.2) rides the same combination to #2.
Florida (#3), Texas (#4) and Louisiana (#5) post the nation's longest cooling seasons - 3,658, 2,921 and 2,779 cooling degree days respectively. Ducts that move air ten months a year accumulate and distribute more of whatever enters the system, and humid-climate condensation adds sweating ductwork to the picture.
Kansas (#6) and Nebraska (#9) outrank most of the coasts. The drivers are old housing (median home age over 50 years in both), near-universal forced-air heat, real summer cooling loads, and semi-arid dust. Nobody markets duct services around the Plains; the data says maybe someone should.
California's cooling season is modest (971 CDD), but 90.6% duct-likely heating, a 50-year median home age, and a dry climate push it into the top ten. The oldest duct systems in mild climates are the ones nobody has looked inside for decades.
Maine (48th), Vermont (47th) and New Hampshire (46th) close the ranking: boiler and radiator heat still dominates, cooling seasons are short, and the climate is wet. Many homes there have no supply ducts at all - which is why our New England city pages lead with dryer vents and retrofit AC rather than pretending otherwise.
Washington ranks 44th statewide - yet its Tri-Cities region is arid agricultural country where dust load rivals the Southwest. State averages are honest about the whole state and silent about pockets; read this index as a macro map, not a verdict on your street.
Subscores (min-max normalized across ranked states):
· Duct prevalence (35%) - share of occupied homes heating with utility gas or electricity (Census ACS 2023 5-year, table B25040), the strongest available proxy for ducted forced-air systems.
· Cooling season (25%) - mean annual cooling degree days, 1996-2025 (NOAA Climate at a Glance, statewide series).
· Dryness (20%) - inverse of mean annual precipitation, 1996-2025 (NOAA CAG) - a dust-load proxy.
· Housing age (20%) - 2026 minus median year built (ACS table B25035).
Limitations we state plainly: heating fuel is a proxy, not a duct census - some gas/electric homes use boilers or baseboards; statewide climate averages hide in-state extremes (see Washington); and this index measures demand conditions, never outcomes. The EPA notes duct cleaning has never been shown to prevent health problems - this index does not claim otherwise.
Unranked states: Alaska, the District of Columbia and Hawaii lack complete NOAA statewide series for the metrics used. We list them unranked rather than reweighting the composite - a smaller honest index beats a padded one.
Every line below is self-contained and attributable - lift freely with credit.
“93.2% of Arizona homes heat with duct-likely gas or electric systems - the practical ceiling for duct prevalence (Census ACS 2023 via DuctDove).”
“Florida runs the nation's longest cooling season: 3,658 cooling degree days on the 1996-2025 NOAA average.”
“Kansas and Nebraska outrank most coastal states for duct-attention conditions - old housing plus Plains dust (DuctDove Duct Attention Index 2026).”
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