This article is part of our seven-part series on the future of cities under President-elect Trump, for which we asked experts in urban planning, city surveillance, and social reform to describe the city they imagine under the policies of the new administration.

“The question is, how far will it grow? Can we have sanctuary regions? Sanctuary states?”

Deporting illegal immigrants was a core tenet of Trump’s campaign, but many major cities have already pledged to stand against him. That list includes Denver, Seattle, New York, L.A., and Chicago, all of which have declared themselves “sanctuary cities,” committing to protect all residents from deportation. Trump has since threatened to cut off millions of dollars of federal aid to these cities in a looming battle between city and federal government.

It’s easy to imagine these urban strongholds going further to protect religious and sexual freedoms, too, turning America’s largest and richest urban centers into a refuge from the authoritarian policies of the federal government.

“In the short run, you may be looking at [federal] mass deportations of illegal immigrants from our cities, and probably a lot of [local] civil disobedience around that,” said one urban expert who preferred to have these comments unattributed. “It’s basically what amounts to a mini civil war inside American cities as [feds] try to deport people.”

Experts suggest that cities may be the best bet for these at-risk groups, despite the problems urban density and visibility introduce. Many cities are essentially giant civic fortresses (many of which have local police forces armed with SWAT-level equipment) that could offer protection from the White House–though, of course, outside their limits mayors would lose such authority. “For me, this starts to look a lot like a Mad Max: Beyond Thunderdome kind of world, where we have the breakdown of nation and the resurfacing of the city as . . . a place that’s almost like a self-governing entity,” says Christoph Lindner, dean of the University of Oregon School of Architecture and Allied Arts. “Today’s megacities economically–in population, industry–are pretty close to having the capacity to function like that.”

What happens when a lot of cities, of varying sizes, team up in one region? Sanctuary zones could emerge, as cities and metroplexes bleed into each other, creating larger regions of refuge and civil disobedience. We could, in essence, see new nations emerge within a nation. Looking at maps of sanctuary cities themselves, you can see that much of the West Coast has pledged to become such a sanctuary–including almost the entire landmass of California.

“The question is, how far will it grow?” asks Lindner. “Can we have sanctuary regions? Sanctuary states?”