PORTLAND, Ore. — The fatal stabbing of two good Samaritans who intervened when a man on a commuter train shouted slurs at two women — both African-American, one in Muslim dress — has reawakened bitter memories of this state’s past and revived a debate over what people here call the “two Oregons,” where islands of tolerance abut places awash in frustration and rage.

“Oregon hasn’t resolved its history,” said Dani Ledezma, the interim executive director of the Coalition of Communities of Color, a group based in Portland. And the harsh language and tone of national politics, she said, are now exacerbating old wounds. “The xenophobia, the racism, the caustic narrative that has been fomented at the national level are also having an impact here and adding to that legacy here in Oregon,” she said.

The Pacific Northwest’s historical attic is full of artifacts that residents would just as soon forget, like the “lash law.” The legislation was passed in 1844, when the Oregon Country, as it was called then, was bigger than Texas — encompassing what is now part of five Western states. The law said that any black person, free or slave, would be “whipped twice a year until he or she shall quit the territory.” Later, leaders prohibited black people from coming to the territory.

Until the early 2000s, Oregon’s constitution still contained language excluding blacks from residency, though its legal clout had been eliminated decades earlier. The template from the early days helped foster a volatile political climate in which extremists of all kinds could find a home, and pick a fight. Along with racists, utopian communities were drawn to the region, advocating everything from socialism to free love, and they found converts and hiding places in remote coastal coves and mountain reaches. In the 1920s, Oregon’s Legislature, dominated by members of the Ku Klux Klan, barred Japanese immigrants from owning or leasing land.

By the 1970s, groups like the Aryan Nations had arrived, spinning out the idea of a mythic Cascadia where the old flames of racial purity would be kept alive and multiculturalism kept at bay. Anarchists dug in, too, and still have a deep presence, regularly turning out — black-shirted and usually masked — to denounce and often clash with the police.

While many Americans may think first of the South as the region where the burden of racial strife weighs heaviest on the nation’s soul and psyche, recent events in Portland serve as a reminder that old battlefields are everywhere.

“The lid is off,” said Detective Elizabeth Wareing, the bias crimes coordinator at the Seattle Police Department. She added that alcohol, drugs and mental illness often played a role in the interactions she investigates.

But she and other experts said that at the same time, there is less and less evidence that any extremist group — old or new — is…