PORTLAND, Maine — Last Friday night, with news of the recent killings of two black men and five police officers blazing across headlines and blaring from TV sets, a crowd marched to the Portland police station and began to chant.

“No justice! No peace! No racist police!” cried the roughly 200 people gathered peacefully to mark the deaths of Philando Castile and Alton Sterling. The chant echoed a line used Thursday in Dallas, Texas, before a sniper shattered the peace of a march against police violence by shooting 13 officers and killing five.

Over the weekend, that message was repeated at protests across the country, some of which broke out in violence. But in Portland on Friday, it was cut short by a lone 17-year-old black activist, David Thete, who silenced the crowd with a reminder that they were protesting police brutality — not the Portland Police Department.

A few days later community leaders converged at Green Memorial African Methodist Episcopal Zion Church on Munjoy Hill, at an event meant to highlight Portland’s commitment to keep the peace in a city largely untouched by the kind of violence that’s dominated recent news cycles. Thete shared the stage with Portland police Chief Michael Sauschuck.

The local protest and the conversation that followed underscore an emerging reality in Portland — the city is approaching an unprecedented era of diversity, and some are questioning how the police can and should change with it.

“Violence can take many forms, and we have largely been fortunate in Portland not to experience those things,” Danielle Conway, dean of the University of Maine School of Law, said. “Our question is, how do we get ahead of this?”

For Conway, the persistent, nagging fear of violence from law enforcement is a fact of being black in America. It’s something she lives with even while feeling at home and welcome in Portland.

“I change my behavior every time I get in the car. I am more guarded. You can’t let your defenses down,” said Conway, who also served 25 years in the U.S. Army, obtaining the rank of lieutenant colonel. “I specifically edit the toys that I allow my child to bring in the car with us because I don’t want to get stopped and have a police officer think that shiny toy is a gun.”

Portlanders take pride in their city’s diversity, but its 15 percent non-white population is notable only relative to Maine overall, which, at 95 percent white, contends with Vermont to be the whitest state in the nation. Portland is far more homogeneous than America’s metropolitan centers and also less diverse than some similar-sized New England cities, such as Pawtucket, Rhode Island, and Framingham, Massachusetts.

But driven by a steady stream of immigration, the city is already twice as diverse as it was 16 years ago and may be on the cusp of a major generational shift.

The Portland public schools are dramatically more diverse than the city overall. This past school year, 58 percent of Portland students were white, while 25 percent were black, 6 percent were Hispanic, 6 percent were Asian and the remainder were of mixed race or Native American, according to district statistics.

Thete said city leaders need a plan on how to avoid the racial violence that sprung up even in cities, such as Dallas, that have focused on de-escalation and community-based policing.

“I want to hear why they think this will not happen in our city,” he said.

Sauschuck said his department is committed to maintaining the close ties between the police force and Portland’s communities of color that were on display at the AME church Tuesday. In January, Portland hired Maine’s first Somali police officer.

But he admitted that’s not enough.

“I need to have more officers of color at the Portland Police Department. That needs to happen. We’re not where we need to be today in 2016,” Sauschuck told the hundreds of people who overflowed the pews at the church Tuesday.

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