“Cronkite” (Harper), by Douglas Brinkley.

Memo to bloggers: Earning the title “most trusted man in America” doesn’t happen overnight.

For longtime “CBS Evening News” anchor Walter Cronkite, decades spent reporting — not rendering opinions — preceded his unofficial coronation as the person to turn to for the straight story.

It didn’t have to be that way. As historian Douglas Brinkley relates in his detailed and insightful biography, Cronkite could have become a crusader like his CBS News colleague Edward R. Murrow. Or he could have turned temporary gigs hosting a morning show or a game show into his life’s work.

Cronkite joined CBS News in 1950, a late arrival to big-time broadcasting — the loyal “Unipresser” had turned down Murrow’s offer of a radio job during the war — but then excelled in the new medium with a wide variety of assignments. Brinkley writes of Cronkite’s stature in 1960, two years before he began a 19-year run as the network’s evening news anchor: “He had come to personify the CBS eye even more than Murrow, and was anointed by the TV viewers as America’s most likable and professional eyewitness to the 20th century.”

Professional but not flawless. Brinkley points out that Cronkite had a sizable ego and found it difficult to fault himself whenever he suffered a career stumble. He stayed neutral on the air during the McCarthyism period, apparently not wanting to risk derailing his own career, and later saw nothing wrong with being a cheerleader for the space program or the environmental movement.

Cronkite allowed his low opinion of Sen. Barry Goldwater to affect his coverage of the conservative Republican, then for years accepted with little skepticism the Johnson administration line on Vietnam. Brinkley notes that Cronkite’s influential break with President Lyndon Johnson on the Vietnam War in 1968 came later than it did for some reporters. The anchorman is reported to have urged Robert Kennedy to run for president, and he was known as a soft interviewer, especially with presidents, regardless of party.

Still, in those three decades when hardly a day went by without Cronkite appearing on CBS, his overall reputation for honesty and evenhandedness was enviable and contributed greatly to establishing the medium’s standards. That made the cold shoulder Cronkite received in the 1980s from the new regime at CBS difficult to take. The million-dollar contract he enjoyed for many years, Brinkley writes, was more about preventing the CBS icon from publicly criticizing the company and his evening news replacement, Dan Rather, than having him contribute to its airwaves.

Brinkley’s impressive chronicle of one of the century’s great journalists burnishes Cronkite’s reputation anew. It’s a celebration of the triumph of hard work, dedication and the belief that getting the story and getting it right mattered most.