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Days of 90°F or hotter and Median household income (model-based)

Counting counties equally, Days of 90°F or hotter and Median household income (model-based) have a link of -0.09 across 3,089 counties, on a scale from −1 to +1. Giving bigger places more weight asks about the average resident rather than the average place, and it flips the link to +0.19. Neither figure is likely to be chance. So this is a real disagreement about who is being described.

Flips when bigger places count more

Every place, plotted

One dot for each place reporting both measures. Hover over or tap a dot to see its name and values. The thin line is the straight line that best fits the dots. The bold line, shown for counties, is the link after adjusting for density, income and education. A dot far from the lines is a place that does not follow the pattern.

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What each measure is

Days of 90°F or hotter

The number of days in the year when the high temperature reached 90°F or more. The high is the average over the county of NOAA's daily map of weather station readings, made of squares about 3 miles wide. So a county with hot valleys and cool mountains counts fewer days than its hottest town. A state's figure is the average of its counties, each weighted by its land area. Lower 48 states only, from 1951.

NOAA NCEI nClimGrid-Daily · NOAA NCEI nClimGrid-Daily v1.0.0 county averages (prcp/tmax/tmin, scaled), hot_days; states, counties averaged by land area

Median household income (model-based)

The income of the middle household. It is an estimate from a statistical model that combines survey answers with tax and government-program records.

Census SAIPE · Census SAIPE SAEMHI_PT

Highest and lowest

Where each measure is highest and lowest among the places reporting both (2023), with the other measure beside it. This is shown for every size of place where both are published. Metro-area values are added up from their counties. A measure that cannot be added up across counties, such as a middle value (median), has no metro figure. Counts are shown per 1,000 residents, since raw totals would only list the largest places. Cities and towns and ZIP codes are shown where the Census survey or the CDC publishes them; most other sources stop at the county. They are shown for places of 5,000 residents or more, and only where the survey’s margin of error is small enough for the figure to be usable. The CDC publishes its health estimates for cities in a version adjusted for age, so places with older or younger people can be compared fairly, but not for ZIP codes.

Counties

By days of 90°F or hotter

Days of 90°F or hotterMedian household income (model-based)
Highest
Starr County, TX196$38,824
Zapata County, TX192$41,688
Hidalgo County, TX189$53,160
Brooks County, TX187$36,695
Jim Hogg County, TX186$44,736
Lowest
Teller County, CO0$88,089
Summit County, CO0$105,140
San Juan County, CO0$102,690
Saguache County, CO0$47,829
Routt County, CO0$112,380

By median household income (model-based)

Days of 90°F or hotterMedian household income (model-based)
Highest
Loudoun County, VA19$173,660
Santa Clara County, CA22$154,570
San Mateo County, CA1$151,000
Los Alamos County, NM11$146,210
Falls Church city, VA13$145,760
Lowest
Claiborne County, MS110$28,579
Holmes County, MS96$30,542
Humphreys County, MS99$31,538
Buffalo County, SD26$32,803
Leflore County, MS91$33,945
States

By days of 90°F or hotter

Days of 90°F or hotterMedian household income (model-based)
Highest
Texas118$75,778
Louisiana114$58,273
Florida105$73,283
Arizona90.2$77,158
Mississippi89$54,386
Lowest
Rhode Island0.396$83,518
Vermont0.566$80,626
New York0.947$82,052
Maine1.16$73,463
New Hampshire1.69$97,031

By median household income (model-based)

Days of 90°F or hotterMedian household income (model-based)
Highest
Massachusetts3.43$99,750
New Jersey12.5$99,716
Maryland17.3$98,568
New Hampshire1.69$97,031
California52.9$95,473
Lowest
Mississippi89$54,386
West Virginia3.56$55,875
Louisiana114$58,273
Arkansas63.5$58,748
Kentucky13.8$61,099
Metro areas — Median household income (model-based) is not published for metro areas

By days of 90°F or hotter

Days of 90°F or hotterMedian household income (model-based)
Highest
Rio Grande City-Roma, TX196—
Zapata, TX192—
McAllen-Edinburg-Mission, TX189—
Alice, TX178—
Yuma, AZ176—
Lowest
Youngstown-Warren, OH0—
Wooster, OH0—
Wheeling, WV-OH0—
Waynesville, NC0—
Watertown-Fort Drum, NY0—

Counties furthest from the pattern

Compared with the straight line that best fits all 3,108 counties: the five with far more median household income (model-based) than their days of 90°F or hotter would suggest, and the five with far less.

Days of 90°F or hotterMedian household income (model-based)
Above the line
Loudoun County, VA19$173,660
Santa Clara County, CA22$154,570
San Mateo County, CA1$151,000
Los Alamos County, NM11$146,210
Falls Church city, VA13$145,760
Below the line
McDowell County, WV2$35,161
Buffalo County, SD26$32,803
Bell County, KY3$35,566
Owsley County, KY12$35,000
McCreary County, KY4$36,348

Two series, one county

Both measures over time for a county you pick. The two charts are stacked, so they share only the years along the bottom. You can pick from the thirty largest counties reporting both. This panel covers 2010–2024, and a measure published only once shows as a single dot.

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Every version of the link

Each row measures the same link, from −1 to +1, in a different way. If the rows mostly agree, the link does not depend on one choice of method.

Before adjusting for anything-0.2443,089 counties reporting both
After adjusting for density, income and education-0.085the part of the link that is not just how urban, rich and educated a place is
Also adjusting for population size-0.099size taken out as well as density
Also comparing only within each state-0.061each county is compared only with others in its own state, so this is no longer a comparison between states
Also holding winter sunshine equal-0.098compares counties that get the same sunlight in winter as well. If this is much weaker, part of the link is a difference between sunny and grey regions (more)
Giving bigger counties more weight+0.188the adjusted link for the average resident rather than the average county. With this weighting, the data counts for about 284 equally weighted counties
Middle value inside single states-0.065the link worked out inside each of 39 states with at least 20 counties reporting
Using ranks, after adjusting-0.109uses each county’s rank, not its value, so a few extreme counties cannot create the link

How much to believe it

Could it be chance?

The p-value is the chance of seeing a link this strong if there were really none. A value of 0.05 or less means the link is unlikely to be chance. Very small values are written in short form: 3.1e-16 means 0.00000000000000031, and the bigger the number after “e-”, the smaller the value. Treating every county as a separate case gives p = 2.3e-6. But counties in the same state tend to resemble each other, so the better figure allows for that: p = 0.010. The site tested 32,131 pairs, and testing so many turns up some flukes. The q-value allows for that too. For this pair it is 4.3e-6.

Do nearby places look alike?

Moran’s I measures how much nearby places look alike: 0 means no map pattern, and higher means neighbours are more similar. For the part of each county that the adjustment leaves unexplained, it is +0.09 (p = 0.001). Once the adjustment is made, little map pattern is left.

Did they change together?

The figures above compare counties at one moment. This asks a different question: where days of 90°F or hotter rose most, did median household income (model-based)move too? Each county’s change is compared with the average change in its own state. That takes out ups and downs that hit a whole region at once. Each change is the gap between two estimates that both contain some error. That error pulls these links towards zero, so a weak one is weak partly for that reason. The q column shows whether a link could be a fluke, allowing for the many pairs tested: 0.05 or less means it is unlikely to be chance.

PeriodCountiesChange togetherWithin statesq
2014–2019 the main test: each Census survey figure averages five years, and these two do not overlap; before the pandemic3,099+0.09+0.060.175
2019–2023 a repeat check: its two five-year survey figures both include 2019, and it covers the COVID years3,099-0.11-0.020.657

Over the main period, any link between the changes could easily be chance. How change is measured.

Related pairs

Association only. Nothing here shows that either measure changes the other. This describes counties, not the people in them. Two measures going together across places does not mean the same people have both. How the US county data works · Explore Days of 90°F or hotter and Median household income (model-based)