Johnson resisted working in New York journalism to avoid being compared to his father. He worked for nearly a year at the Wilmington (Del.) News-Journal before joining the Star as a reporter.
He covered a wide range of stories, from earthquakes to President John F. Kennedy's inauguration to foreign conflicts, according to the book, "National Reporting: 1941-1986." He also wrote a series on blacks in Washington.
His reporting eventually took him to Selma, in the heat of summer, to report on the civil rights movement.
Months earlier, in March 1965, hundreds of marchers bound for the state capital of Montgomery had been brutally beaten by state and local law officers. Martin Luther King, Jr., came to the city, and after a federal judge found that the demonstrators had a right to march, they completed their journey later that month.
Johnson sought to further explore the issues that the march and demonstrations had raised.
"Haynes had roots in the South," Balz said. "He was raised in New York, but he had Southern roots. He had a special appreciation for the civil rights struggle and what African-Americans were going through."
Johnson and his father are the only father and son to win Pulitzer Prizes for reporting.
It wasn't long before Ben Bradlee, the newly appointed executive editor of The Washington Post, came calling. As Bradlee was seeking to elevate the newspaper, he recruited both Johnson and The New York Times' David S. Broder to strengthen the paper's political reporting.
"He reached out, held out his hand, and I grabbed it, and that was it," Johnson recalled in Jeff Himmelman's 2012 biography of Bradlee. "There was no contract, nothing. It was just, 'Come, we want you,' and I've never forgotten that."
Johnson's books include "The Battle for America 2008: The Story of an Extraordinary Election," (2009) with Balz; "The Best of Times: America in the Clinton Years" (2001); and "The System: The American Way of Politics at the Breaking Point" (1996) with Broder, who died two years ago.
Johnson and Broder helped transform Washington reporting, getting outside the Beltway to talk with voters about candidates and issues, rather than letting politicians dictate coverage. Both wove that reporting into broader articles that examined the mood of the country and the inner workings of government.
"Hayes was a giant," journalism professor and author Carl Sessions Stepp commented on the Merrill College's website. "He had the mind of a scholar and the soul of a regular citizen, and nobody has ever better combined insider digging and outside-the-Beltway pulse-taking."
Gene Roberts, who helped lead The Philadelphia Inquirer and The New York Times and co-authored a book on media coverage of the civil rights movement, said he was amazed with Johnson's work ethic.
"I think he was one of the most important reporters in the country during his journalistic career and later as he got more into books," Roberts said. "I was amazed. Most writers take a breather between books, but when he finished one book he always started immediately on another book."
Johnson and Roberts taught together at the University of Maryland. Roberts said Johnson was an inspirational teacher and a serious historian. He also successfully worked to have his father's "Waterfront" articles printed in book form in 2005.
The university said Johnson had begun work on a 19th book, looking at the speed with which breaking news was covered in the social media era. On Thursday night, Johnson phoned his teaching assistant from the hospital to say he was bored and to ask for some reading material so he could work on the book, the university article said.
Johnson's first marriage, to Julia Ann Erwin, ended in divorce. They had three daughters and two sons. Johnson and Oberly, an associate judge on the District of Columbia Court of Appeals, married in 2002.
Zongker contributed from Washington.