When riots erupted on April 4, 1968, engulfing Washington, Chicago and dozens of other American cities in violence, journalists and scholars tried to make sense of the chaos.

Newspapers covered the arson, shattered glass and occasional bloodshed, focusing on its most immediate cause, the assassination of the Rev. Martin Luther King Jr. earlier that day. Monographs chronicled the racial tensions of a more distant past, analyzing urban segregation and racially motivated mobs from the turn of the century to the Depression.

Most of the scholarship, however, failed to analyze institutional forces during World War II and the decades that followed, when millions of African Americans migrated to cities outside of the South, when high-rise towers sprouted up in predominantly black neighborhoods and policymakers announced a cheery-sounding doctrine known as “urban renewal” – what writer James Baldwin would later dub “Negro removal.”

With few exceptions, the impact of these policy decisions went unexplored until 1983, when historian Arnold Hirsch published “Making the Second Ghetto: Race and Housing in Chicago, 1940-1960.” The book sent a jolt through the field of urban history and remains a touchstone for historians, sociologists and journalists such as Ta-Nehisi Coates.

“If you want to understand the Freddie Gray riots” in Baltimore, Coates said in a recent interview, “Arnold Hirsch is telling you why.”

Dr. Hirsch, whose work demonstrated how racism pervaded every stratum of American society, died March 19 at his home in Oak Park, Illinois. He was 69 and had Parkinson’s disease and Lewy body dementia, said his son Jordan Hirsch.

Hirsch was a 19-year-old history major during the King riots, taking classes at the University of Illinois at Chicago, not far from the epicenter of violence on the city’s West Side. His book, he later wrote, “had its beginnings in the afterglow of the fires that illuminated the inner city,” though its exploration of American racism extended far beyond a single city or violent outburst.

“No historian before Arnold Hirsch had written systematically about the process of racial segregation in the post Second World War years,” Thomas Sugrue, director of American studies at New York University and author of “The Origins of the Urban Crisis,” said by email.

Hirsch’s book indicted nearly every level of Chicago society. He described a “hidden violence” in the city, counting more than 500 incidents in which black newcomers were attacked by their white neighbors. Universities and the city government, he wrote, merely draped their racism in terms of “urban renewal,” the razing of “blighted” buildings that primarily housed African Americans.

Arnold Richard Hirsch was born in Chicago on March 9, 1949, and raised in the city’s Rogers Park neighborhood. He was 13 when his father died, and his mother worked at a bank to support the family. (She later married Hirsch’s father-in-law.)

Hirsch received his doctorate in 1978 from the University of Illinois at Chicago and soon joined the University of New Orleans, where he completed “Making the Second Ghetto” and worked as a history professor until his retirement in 2010.

His later work focused primarily on the modern history and politics of New Orleans. Even after his diagnosis of Parkinson’s, Hirsch continued to publish book chapters and scholarly articles and, according to Jordan Hirsch, once served as a witness at a Baltimore trial centered on federal housing policies and segregation.

“Survivors include his wife of 46 years, Roseanne Bernover Hirsch of Oak Park; two sons, Jordan Hirsch of New Orleans and Adam Hirsch of Oak Park; and two grandchildren.