If three decidedly pro-immigration mayors were to offer an immigration policy recommendation to the next president of the United States, what would it be?

Of course, it depends on whom that president ends up being. If it’s Donald Trump, for instance, Phoenix Mayor Greg Stanton would tell him, “The wall is a really, really dumb idea.”

His reasoning, stated during a Democratic National Convention-concurrent forum on immigration policy, is that such a tactic would be bad for the economy. With a population made up of at least 41 percent Hispanics, the Arizona capital suffered from damaged trade relations with Mexico when SB 1070 — the bill that would allow police to detain anyone suspected of being an illegal resident, regardless of their actual status — was legalized in the state, according to the mayor.

“It hurt us badly,” said Stanton, who estimated that “tens of thousands of jobs are directly connected” to trade. Center for American Progress found that the city lost $141 million in tourism dollars because of the bill.

The mantra that “being a welcoming city is good for business” echoed throughout the event, “Strength of the Union: The Power of 240 Years of Immigration,” where three mayors — including Philadelphia’s Jim Kenney and New York City’s Bill de Blasio — discussed best practices for building immigrant-friendly cities in the 21st century.

They were joined by David Lubell, executive director of the Welcoming America; Geisha Williams, president of electric at Pacific Gas and Electric Company; and moderator and Voto Latino CEO and President María Teresa Kumar.

According to Lubell, of the nonprofit that works with more than 100 cities across the country to be more “welcoming” to immigrants, said when programs are in place to help immigrants transition to the city, cities thrive — especially because almost 30 percent of “Main Street” businesses are owned by immigrants.

“Immigration is good for business,” said Williams, a Cuban immigrant who shared her own American Dream story of working with her parents from an early age and feeling pushed to strive for more than they had. Later on, working for companies with strong diversity practices encouraged her to seek out higher positions than she thought she was qualified for.

“Why not me?” she said.

Kenney, who received big applause during his introduction when Kumar announced that he’d reestablished Philadelphia as a sanctuary city for immigrants, brought up police brutality against people color.

“Our immigrant community are not criminals, for the most part,” Kenney said. “You cannot police effectively when the citizenry is afraid of your police.”

Philly has no Latinx police captains, he said. Hiring some would help make the force more culturally sensitive and foster connections with Latinx communities.

The city could use Phoenix as a model: To better relations with law enforcement during the era of SB 1070, Stanton said he encouraged the police department to actively communicate to citizens that they could report a crime without risking deportation.

Communication without borders. Or walls.