His death was announced by son Bill and confirmed by John Halligan, a family friend and hockey historian. Chadwick had been in declining health for a number of years and died while in hospice care.

For 16 seasons, from 1939 to 1955, and despite being blind in one eye, Chadwick was one of the best officials the NHL. He invented and perfected the system of hand signals to signify penalties, and the system is now used throughout the world.

"Bill Chadwick had the confidence and the creativity to introduce hand signals to officiating," NHL commissioner Gary Bettman said. "He had the courage to make the tough calls. His honesty and integrity brought him to the very top of his profession."

William Leroy Chadwick was born in Manhattan on Oct. 10, 1915. He became an amateur hockey player of some note while attending Jamaica High School.

He also excelled at baseball, winning the city championship with Jamaica in 1933 and playing at various times against future major leaguers Phil Rizzuto and Sid Gordon.

But hockey was Chadwick's sport of choice, and he honed his skills on racing skates at Baisley Park and Goose Pond in Queens and at the Brooklyn Ice Palace.

Following high school, Chadwick played under an assumed name at Fordham University. A center, he also starred with the Jamaica Hawks and the New York Stock Exchange Brokers in the Metropolitan Amateur Hockey League.

In 1935, playing for a Met League All-Star Team at Madison Square Garden, Chadwick was struck in the right eye by an errant puck as he stepped onto the ice to face a team from Boston. He spent a week at Manhattan Eye and Ear Hospital, but doctors were unable to restore the vision in the eye.

Despite the injury, Chadwick continued to play hockey with the New York Rovers of the Eastern Hockey League. Then, early in the 1936-37 season, he was hit in his left eye by an opposing player's stick. The injury wasn't nearly as serious as the earlier one, but Chadwick knew his hockey-playing days were finished.

"Nobody loved the game more than I did, but I couldn't take the chance of losing the other eye as well," Chadwick recalled in his autobiography, "The Big Whistle" — written with former Associated Press writer Hal Bock.

In March of 1937, Chadwick was at the Garden watching the Rovers in pregame warmups. He was paged over the public address system and asked to report to the timekeeper's bench. The scheduled referee, Ray Levia, was stuck in a snowstorm, and Tommy Lockhart, the Garden's amateur hockey boss, asked Bill to referee the game.

"Where's the whistle?" Chadwick said.

Chadwick soon caught the attention of NHL president Frank Calder, In 1939, Calder asked Chadwick to join the NHL as a linesman. He accepted and became the NHL's first U.S.-born official, working his first game at the Garden, the Montreal Canadiens versus the New York Americans. A year later, he was promoted to referee.

"There were some prejudices against me being an American and all," Chadwick remembered, "but I had the full support of Calder and his successor, Clarence Campbell. Lester Patrick, the Rangers' general manager, was also a great booster of mine."

As for the hand signals, Chadwick doesn't recall exactly when he started using them. "Somewhere around 1943 or 1944 would be fairly accurate," he told Halligan.

"I know it was during the Stanley Cup finals," Chadwick said. "There was so much noise that I had difficulty communicating with the penalty timekeeper."

Chadwick's signals were not made official by the league until 1956, the year after he retired.

Following his hockey career, Chadwick was general manager of a moving company in Brooklyn, and manager of the Pine Hollow Country Club in East Norwich.

In 1965, at the urging of Emile Francis, the Rangers' longtime general manager and coach, Chadwick embarked on a 14-year broadcasting career, working first on radio with play by play man Marv Albert, and most notably, on television with Jim Gordon for nine seasons

"Bill was a natural for broadcasting even though he wasn't formally trained in it," Francis said. "He and Jim Gordon got more mail than some of our players. For a native New Yorker to do what he did in hockey at that time was really unbelievable."

Arthur Friedman, the Rangers' longtime statistician, dubbed Chadwick "The Big Whistle" in 1969, and the nickname stuck.

"That nickname made me a celebrity," Chadwick recalled.

As a referee, Chadwick worked more than 900 regular-season games, plus a record 42 Stanley Cup finals games, including 13 games in which the Cup was decided.

In 1964, Chadwick was inducted into the Hockey Hall of Fame, only the fifth official, and the first American-born official, to be so honored. In 1974, he was inducted into the U.S. Hockey Hall of Fame. In 1975, he won the Lester Patrick Award for outstanding service to hockey in the United States.

Chadwick retired in 1988 to Cutchogue on Long Island's north shore.

He was preceded in death by wife Millie. In addition to son Bill of Malibu, Calif., Chadwick is survived by five grandchildren, and long-time companion Joan Langemyr of Cutchogue.