Tom Wicker, one of postwar America’s most distinguished journalists, who wrote 20 books, covered the assassination of President John F. Kennedy for The New York Times and became the paper’s Washington bureau chief and an iconoclastic political columnist for 25 years, died on Friday at his home near Rochester, Vt. He was 85.

The cause was apparently a heart attack, said his wife, Pamela Wicker.

On Nov. 22, 1963, Mr. Wicker, a brilliant but relatively unknown White House correspondent who had worked at four smaller papers, written several novels under a pen name and, at 37, had established himself as a workhorse of The Times’s Washington bureau, was riding in the presidential motorcade as it wound through downtown Dallas, the lone Times reporter on a routine political trip to Texas.

The searing images of that day — the rifleman’s shots cracking across Dealey Plaza, the wounded president lurching forward in the open limousine, the blur of speed to Parkland Memorial Hospital and the nation’s anguish as the doctors gave way to the priests and a new era — were dictated by Mr. Wicker from a phone booth in stark, detailed prose drawn from notes scribbled on a White House itinerary sheet. It filled two front-page columns and the entire second page, and vaulted the writer to journalistic prominence overnight.

Nine months later, Mr. Wicker, the son of a small-town North Carolina railroad conductor, succeeded the legendary James B. Reston as chief of The Times’s 48-member Washington bureau, and two years later he inherited the column — although hardly the mantle — of the retiring Arthur Krock, the dean of Washington pundits, who had covered every president since Calvin Coolidge.