Sen. John F. Kennedy sits next to a playback of his televised appearance in Milwaukee for the Wisconsin presidential primary two days later. (Associated Press / April 3, 1960)

Although every network and its Dallas affiliate covered the story, progressing through the stations of rumor, unconfirmed report and confirmed report, it's Cronkite who has come to stand for the day. On the air for hours in his shirt sleeves — he never thought to put on his jacket, earning him an admonishing note from his boss, Frank Stanton — taking his glasses on and off depending on what he needed to read or see, he endured what he later described as a "running battle between my emotions and my news sense."

His brief, quickly swallowed show of emotion as he delivered the news, finally confirmed, makes him seem at once one with his viewers and a trustworthy steward of their feelings — a relationship that continued on through the space program and the Vietnam War and, indeed, into Cronkite's retirement.

There is something humble and unadorned about these reports that, even in their stumbling, fits the awfulness of the occasion better than would the cluttered, hyperactive graphics of modern TV news, which so often — especially in times of crisis, it can seem — runs to competitive vulgarity and exploitation. They are, in a way, not unlike Dealey Plaza itself, surprisingly ordinary for such a world-shattering event.

In contrast to the assassination, whose random visual record renders the event permanently hazy, shooter Lee Harvey Oswald's 48 hours at Dallas police headquarters were accompanied by a literal crush of reporters and multiple recordings of his every public appearance. His own assassination, by Jack Ruby, was broadcast live with a sharpness, vividness and immediacy that paradoxically makes it seem unreal, like play acting, an avant-garde update of "Julius Caesar." It was the starting gun, if you'll excuse the expression, for the theater of chaos the decade would become; Gil Scott-Heron's much-cited phrase to the contrary, the revolution was very much televised.

PHOTOS: How TV reacted to JFK's assassination

New President Lyndon B. Johnson, sworn in during the flight back to Washington and conscious of the need for visible continuity, ordered that the arrival of Kennedy's casket back in Washington be televised live. (Johnson, though in no sense telegenic, would appear on TV with even greater frequency, if with stricter control, than his predecessor.) When JFK was laid in state at the Capitol, NBC stayed on the air all night — a rarity then — to show the crowds filing past. The funeral procession from the Capitol to the White House to St. Matthew's Cathedral to Arlington National Cemetery was broadcast from beginning to end. Fifty cameras, shared by the networks, recorded his progress.

It would all look different now, of course, in our 5-million-camera world. Special music would be written, special graphics animated. Television itself, which McLuhan had defined as a "low definition" medium that required the viewer to fill in details, is now something quite the opposite — a flood of details, in high-definition, with a surfeit of overlapping voices, fighting to be heard.

But more information does not necessarily equal more clarity. Walter Cronkite, putting on his glasses to read a bulletin and taking them off to tell a nation what it said, is sometimes all you need.