Even as Mr Trump cut a swathe through the Republican primaries earlier this year very few voters cited it as their main reason for voting. But those who did voted for him.
“If you want to see Trump’s America come to Arizona,” B Loewe, a Hispanic community organiser in Phoenix, said.
Arizona has been among the most aggressive states in the country in enforcing a tangle of immigration laws that rely on co-operation between various federal agencies and local law enforcement. No one has shown more enthusiasm for hounding illegal immigrants than Joe Arpaio, who styles himself as “America’s toughest sheriff” and has spent 23 years in his post in Maricopa County, Arizona. His approach has made him a hero to right-wingers and earned him a spot as an occasional warm-up act at Trump rallies.
Some Arizonans are happy to help Mr Arpaio’s cause. Shouldering his assault rifle under the midday sun in the Sonoran desert, Harry Hughes scanned the rocks above him for signs of life. “This is the front line,” he said, standing on a scrubby mountain pass studded with cacti and strewn with empty water canisters and food wrappers left by migrants slipping into the US. Mexico was 70 miles away.
Mr Hughes, 53, an unemployed National Socialist in contact with Ku Klux Klan members, belongs to the Mountain Minutemen, one of a number of armed volunteer groups patrolling a remote, unforgiving section of the Arizona border through which a large proportion of the country’s drugs and illegal immigrants arrive. Last month his group endorsed Donald Trump for president. Their website declares: “If Trump wins . . . we get the wall!! If Killary wins, we lose the border!”
Mr Trump intends to sweep both programmes away. Hillary Clinton has promised a route to citizenship in her first 100 days.
Where both main parties agree is that America’s current immigration policy is not working. In Arizona that failure is on display every day in the large Tucson courtroom where sentencing for Operation Streamline, a federal programme of fast-track immigration prosecutions, takes place.
On a recent afternoon 50 men and women were marched in shackled at the wrist, waist and ankles and still wearing the dirty clothes they had on when they were intercepted at the border one, two or three days earlier.
They were lined up seven at a time, in front of lawyers they had met for only a few minutes, asked by Judge Bernardo Velasco if they understood the consequences of pleading guilty to entering the country illegally and then sentenced to between one and six months in detention, followed by deportation. It took 45 minutes to clear the room.
Afterwards, in his large office decorated with a stuffed animal head, a samurai sword and a poster of Mae West, the judge, whose grandparents came to the US from Mexico, said he understood that law enforcement had to respond to public pressure, “even if it’s the wrong thing”. But he added: “Whatever the western frontier was it was always populated by industrious and courageous people. Well, the people that are walking across the desert are the kind of industrious and courageous people that we want, if you think about it. They fit what used to be our criteria. The problem is we don’t admit we like cheap labour like we did when my grandparents came over.”
Mary Ann Mendoza extended her right arm to show the five coloured bracelets on her wrist, each commemorating a US citizen killed by an undocumented immigrant.
One of them was for her son Brandon Mendoza, an Arizona police sergeant, who was hit head-on by a driver who had been in the US illegally for two decades despite court appearances and a criminal history.
Raul Silva-Corona had driven for 35 miles the wrong way down four freeways before the crash, she said. “He was three times the legal limit drunk and high on meth”.
After the tragedy in 2014 she was “a zombie” for two weeks. Then she began to investigate similar deaths and became furious at what she saw as the US’s lenient treatment for illegal immigrants.
In July she made an impassioned speech at the Republican National Congress in which she said: “A vote for Hillary [Clinton] is putting all our children’s lives at risk. It’s time for Donald Trump.”
The Republican nominee has met “hundreds” of parents like her and she has spoken at all the Trump rallies in Arizona.
Like Mr Trump she wants a border wall and zero tolerance for existing illegal immigrants. “We’ve busted our ass helping the world for how many years?” she said. “It’s time to take care of America and Americans.”