Pima County keeps Democrats' Arizona anchor — but the 2020 peak is fading

Pima County is Arizona's second-largest county by population and the home of Tucson, and that combination gives it outsized weight in a state that has become one of the most closely contested on the national map. Arizona's statewide outcomes are built from a small number of large, Democratic-leaning urban counties offsetting a wide field of smaller, Republican-leaning rural ones. Pima is one of those urban anchors. When a Democrat wins Arizona, the margin banked in Pima County is almost always part of the story; when a Democrat falls short statewide, softness here is often the reason. That makes the county a durable barometer for how the state's coalition is holding up.

The numbers

Pima County has voted Democratic in each of the last three presidential elections, but the size of that advantage has moved. In 2016 the county finished at D+13.5. In 2020 it widened to D+18.7, a clear high-water mark. In 2024 it came back down to D+15.2, with 292,450 Democratic votes to 214,669 Republican votes out of 513,176 ballots cast — a Democratic edge of roughly 77,781 votes.

Read across the full window, the trend is modestly Democratic: the net shift from 2016 to 2024 is 1.7 points toward the Democrats. But the more recent movement runs the other way. From 2020 to 2024 the county moved 3.5 points toward Republicans, giving back most of the gains it had posted four years earlier. In plain terms, Pima is a bit bluer than it was in 2016, but it stepped back from its 2020 peak. Both things are true at once, and holding them together is the key to reading the county honestly.

What is driving it

The pattern reflects what Pima County is. Its population and its votes are concentrated in Tucson, a mid-sized desert city anchored by the University of Arizona. Large university towns tend to produce reliable Democratic majorities, and Tucson's urban core delivers the bulk of the county's margin. Around that core sit suburban neighborhoods, retirement communities, and a wide stretch of exurban and rural desert that leans more Republican and tempers the citywide totals.

Pima is also a Southern Arizona border county with a substantial Latino community woven through its history and economy. Latino voters have long been an important part of the Democratic coalition here, and shifts in how that broad and internally varied electorate votes can move a county like this one in either direction from cycle to cycle. The 2020-to-2024 pullback is consistent with the kind of modest urban softening seen in many places nationally, without erasing the county's underlying Democratic lean.

What to watch

The honest headline for 2026 and 2028 is that Pima County remains a Democratic county, and nothing in these three results suggests it is about to stop being one. The double-digit Democratic margin has been stable enough that the reasonable base case, if the trend holds, is another comfortable Democratic win rather than a flip.

The more interesting question is direction, not side. The number to watch is whether the county continues drifting back from its 2020 high or steadies out around its 2024 level. If the 3.5-point move toward Republicans between 2020 and 2024 turns out to be a one-cycle correction, Pima could settle back into the mid-to-high teens. If instead that softening extends into the next two cycles, the margin could keep narrowing toward — though still comfortably above — its 2016 baseline of D+13.5.

For anyone tracking Arizona statewide, Pima's raw margin is the metric that matters most. Because the county is one of the Democrats' two essential urban engines, even a few points of erosion here has to be made up somewhere else. A Pima margin holding near D+15 keeps the statewide picture familiar; a margin sliding back toward D+13 would be an early, quiet signal that Arizona's balance is tightening again. Watch the margin, not the winner.