Voters in Maricopa County, the largest in the US swing state of Arizona, will play a key role in deciding whether Kamala Harris or Donald Trump wins the White House in November.
Here are five key facts about the county:
America’s hottest big city
Maricopa County is home to Phoenix, Arizona’s state capital, where the average high temperature exceeds 100 degrees Fahrenheit (37.7 Celsius) for four months of the year.
The sun-drenched metropolis was named in the late 19th century after being founded on the ruins of an ancient native civilization. The small settlement, located in the northern Sonoran Desert, was worth just $550 after the US Civil War.
Irrigation helped Phoenix grow from a sleepy frontier town dotted with saguaro cacti into a center for citrus, cattle and cotton. Its hot, arid climate later made it an attraction for tuberculosis patients.
After World War II, immigrants, retirees and young families seeking warm weather and low costs flocked to the area, dramatically increasing the population thanks in part to the advent of air conditioning.
Phoenix is now the nation’s fifth-largest by population, surpassing Philadelphia. More than 1.6 million Americans live in the financial services and manufacturing hub, according to the latest US Census.
Historically Republican
The county — home to about 4.5 million people, or 62 percent of Arizona’s population — is the second-largest voting jurisdiction in the country, and was until recently a reliable Republican stronghold.
“The real significant election, I think, was in 2016 when Trump took the county just by three percentage points. Four years earlier, it was taken by Mitt Romney by 11 points,” said David Berman, professor emeritus of political science at Arizona State University.
President Joe Biden beat Trump in Maricopa County by more than 45,000 votes in 2020, helping him break a nearly eight-decade winning streak for Republican presidential candidates in Arizona.
Berman said Trump’s right-wing agenda has alienated some Arizonans who prefer more centrist Republicans, such as late US senator John McCain.
Hispanic population growing
The Hispanic population in Maricopa County has grown to account for nearly a third of all residents, according to the latest census.
That change is part of a larger trend spurred in part by rising immigration. Between 2010 and 2020, Arizona’s Hispanic residents increased by 16 percent — faster than the state’s overall population growth.
“There has been a concentrated effort to bring out the Hispanic vote as well as the Native American vote,” Berman said of the groups, which tend to vote Democratic.
He added that there have also been “some gains for Democrats” as people seeking cheaper housing and better job opportunities continue to move to Arizona from more traditionally liberal states such as California.
Increasingly independent
Despite Arizona’s Republican voting history and recent Democratic inroads, more than a third of Maricopa County residents are not affiliated with either party.
Roughly 34 percent of active voters are registered as “other,” according to the county’s most recent data — rivaling Republicans at 35 percent and surpassing Democrats at 28 percent.
That proportion has grown steadily over the past few years, making the county’s election results more unpredictable.
“Maricopa County still has quite a bit of red in it, and these swing voters will generally opt for more traditional Republicans,” rather than Trump’s hard-right brand, said Paul Bentz, senior vice president at Phoenix-based public affairs firm Highground.
“We are not a purple state,” he said, referring to an area evenly mixed between Republican red and Democratic blue.
“We are a red state with purple spots.”
Early voting dominates
About 80 percent of the county’s voters cast early ballots in 2020 and 2022, mirroring a statewide trend that predates the coronavirus pandemic.
“We’ve been doing it for over three decades. Republicans are really the ones that brought early voting to the state of Arizona,” Bentz said.
In 1991, the state legislature allowed voters to request an absentee ballot for any reason, making the practice widely available. More than a decade later, Arizona created a program that automatically sends voters a ballot for each upcoming election.
The growth of mail ballots since the pandemic has made vote verification and counting a days-long process. Most US news networks took more than a week to call the state for Biden in 2020.