Booker T. Washington, a prominent African American of his era after whom the Booker T. Washington High School in Tulsa was named in 1913, ostensibly called Greenwood "the Black Wall Street", a name soon adopted by many others. Yet according to Johnson, the designation is a misnomer given the absence of banking and investment undertakings, and the community itself being "one of necessity" that was the product of state-sanctioned segregation.

In November 1907 Oklahoma, right upon its admission as a state, adopted racial segregation laws as its first order of business. Commonly known as Jim Crow laws, they targeted the black as well as other peoples of color, with measures to disenfranchise them and undo their political and economic gains.

Nine years later the city of Tulsa mandated residential segregation by forbidding black or white people from residing on any block where 75 percent or more of residents were members of the other race.

Abutting Tulsa, "Greenwood District is in essence black mainstream for those unable to participate in the white-dominated economy", Johnson said.

One result of this was that wealth created by black Tulsans had nowhere else to go but to stay within the 35 blocks, in the form of 200 black-owned businesses, and many affluent families, including four black millionaires. The discovery of oil and natural gas, which led Tulsa to proclaim itself the "Oil Capital" starting in the 1910s, also contributed to the phenomenon.

Greenwood became known across the US as a model of blacks working productively together and of economic independence. "What was happening in the Greenwood District wouldn't be contained within the Greenwood District," said Karlos Hill, associate professor of African American studies at the University of Oklahoma, in a previous interview. "Some individuals would be pressing for greater inclusion, political and civil rights."

Yet what was seen by all African Americans, especially those from the racism-riven Deep South, as "a symbol of what was possible"－to quote Hill－was also "an anomaly", according to Johnson.

"Having thrived at a time when the Ku Klux Klan was incredibly active in Oklahoma, the community had, up to the point of the massacre, dodged bloody white-on-black violence that had erupted across the US in what's known today as the Red Summer of 1919. All it needed was a sort of match, an igniter tossed on the embers."

That trigger event took place on May 30, 1921, involving Dick Rowland, 19, a shoeshine boy, and Sarah Page, 17, a white girl who was an elevator attendant in the Drexel building in downtown Tulsa.

"The boy went to the building, boarded the elevator, something happened and Sarah Page began to scream," Johnson said. "They both ran out of the elevator. What happened there we'll likely never know. But the next day, Rowland was arrested and taken to the court."

That same afternoon, the local paper The Tulsa Tribune ran a highly inflammatory article with the headline "Nab Negro for Attacking Girl In an Elevator", accompanied by an editorial titled "To Lynch Negro Tonight"－something that a white mob immediately sought to do, by gathering on the lawn of the city courthouse, where Rowland was in jail on the top floor, and demanding that he be handed over.