Portland is, famously, the whitest big municipality in the United States, which gives it some margin for error to do dumb stuff. For example, from Oregon Live:

Portland police to halt, purge all gang designations Updated on September 8, 2017 By Maxine Bernstein mbernstein@oregonian.com The Oregonian/OregonLive Portland police next month will end their more than 20-year-old practice of designating people as gang members or gang associates in response to strong community concerns about the labels that have disproportionately affected minorities. The Police Bureau recognizes that the gang designations have led to “unintended consequences” and served as lifelong barriers for those who have shunned the gang lifestyle and tried to get jobs, said Acting Tactical Operations Capt. Andy Shearer. A review by Oregonian/OregonLive reporter Carli Brosseau last year found that of the 359 “criminal gang affiliates” flagged in Portland’s database as of last summer, 81 percent were part of a racial or ethnic minority.

From The Oregonian last year:

Who’s on Portland’s gang list? November 4, 2016 at 5:10 AM … By far the largest block — 64 percent — was black, compared with just 7.5 percent of the city’s population who are black or black and some other race.

In contrast, Los Angeles under former top cop Bill Bratton started a program of coming down like a ton of bricks on even low level gang members, rounding up entire gangs in mass arrests. The 2014 article “The End of Gangs” by Sam Quinones (author of Dreamland) explained how Los Angeles had made big progress against crime by using the Racketeer Influenced Corrupt Organization (RICO) law to round up low level losers on gang membership lists:

The 2006 case against HLP was the first in Los Angeles to use RICO statutes on foot soldiers as well as gang leadership. Street gangs had previously been seen as small fry, but, by the mid-2000s, “the culture changed in terms of using this great tool,” says Jim Trusty, chief of the U.S. Justice Department’s Organized Crime and Gang section in Washington, D.C. … Prosecuting street gangs has meant abandoning the previous focus on kingpins. “‘Cut off the head and body dies’ just isn’t true” when it comes to Southern California street gangs, says Brunwin. “You have to go after everyone—anyone who had anything to do with, supported, or touched the organization. You have to have an effect on the structure, its daily operation. The only thing that works is adopting a scorched-Earth policy.”

Basically, whoever happens to be the gang leader at the moment isn’t usually an irreplaceable criminal mastermind. The most important distinction isn’t between low-level gang members and high-level gang members, it’s between gang members and non-gang members.

Since 2006, there have been more than two dozen RICO indictments in Southern California, targeting Florencia 13, Hawaiian Gardens (HG-13), Azusa 13, Five-Deuce Broadway Gangster Crips, Pueblo Bishop Bloods, and many more of the region’s most entrenched and violent gangs. Most of the indictments have dozens of defendants; the Florencia case had 102, while Hawaiian Gardens, in 2009, was one of the largest street-gang indictments in U.S. history, with 147. … Most of the Southern California RICO prosecutions have instead swept up large numbers of street gang members. Leaders of prison gangs like the Mexican Mafia usually aren’t even charged in these prosecutions, and are referred to as “unindicted co-conspirators.” “In prosecuting the members, you make [prison-gang leaders] powerless,” Brunwin says. “If no one’s out there on the street doing their work, then they’re just guys in cells.” Southern California RICO cases have sent large numbers of street-gang soldiers to prisons in places like Arkansas or Indiana, where no girlfriend is coming to visit.

Now, Quinones’s expertise is with Spanish-speaking criminals, so I don’t know from reading him whether this system works as well with black criminals. Judging from reporter Jill Leovy’s book on black murderers in South Central L.A., Ghettoside, an awful lot of black-on-black killings are Disorganized Crime (she cites “unwanted party guests” as a classic cause of homicides).