Dan Rooney, the longtime Pittsburgh Steelers chairman who led the NFL’s diversity efforts for decades, has died, the team announced Thursday.

He was 84.

Rooney’s first job with the Steelers, a team his family has controlled since 1933, was as a water boy at age 12 and he began working in the front office after he graduated from Duquesne University in 1955. He eventually served as general manager and ran the day-to-day operations of the club from 1975 through 2003 when Dan Rooney’s son, Art Rooney Jr., took over those duties.

The Rooneys and the Maras, who have controlled the New York Giants since 1925, are considered the first families of the NFL, though it wasn’t until the NFL-AFL merger announced in 1966 that the Steelers became a powerhouse.

The Steelers shifted to the American Football Conference in 1970, the same season the franchise began play at Three Rivers Stadium, and Pittsburgh became the most dominant team of the decade led by the likes of Terry Bradshaw, Jack Lambert, Franco Harris and head coach Chuck Noll. The team won six consecutive AFC Central titles to close out the decade, a run that included four Super Bowl titles. In all, the Steelers won four Super Bowls in six years during that time.

Tributes began across social media and other places soon after Rooney's death was announced. Dallas Cowboys owner Jerry Jones released the following statement following the news:

“This is a sad day for anyone who has had an association with the NFL.  Whether it be fans, players, coaches, broadcast personnel, media, team owners or club employees, Dan Rooney’s influence touched us all—and made all of our lives better.

“The Rooney’s are a royal family in the National Football League, and Dan more than capably followed in the footsteps of his father, Art, a league founder.  He shaped the league with instincts, wisdom and a soft-spoken velvet touch.  He was a steward and a guardian for the growth and popularity of the NFL, because he loved the game so much.

“My last in-person visit with Dan came just moments after our teams played in Pittsburgh in November.  It was a thrilling game that came down to the last possession, and Dan came to the Cowboys locker room to congratulate our team.  It was a touching act of kindness and sportsmanship, and a moment that will forever remind me of the dignity and class with which he lived every day of his wonderful life.

“Our thoughts are with Pat, Art II and all of the Rooney family.  Dan Rooney’s spirit will be remembered and embraced for as long as young boys and men play this game - and for as long as people gather to watch and enjoy it.”  

Others paid their respects Thursday as well.

"Few men have contributed as much to the National Football League as Dan Rooney," NFL Commissioner Roger Goodell wrote in a statement. "A member of the Pro Football Hall of Fame, he was one of the finest men in the history of our game and it was a privilege to work alongside him for so many years. Dan’s dedication to the game, to the players and coaches, to his beloved Pittsburgh, and to Steelers fans everywhere was unparalleled. He was a role model and trusted colleague to commissioners since Bert Bell, countless NFL owners, and so many others in and out of the NFL. A voice of reason on a wide range of topics, including diversity and labor relations, Dan always had the league’s best interests at heart.  For my part, Dan’s friendship and counsel were both inspiring and irreplaceable. My heart goes out to Patricia, Art, and the entire Rooney family on the loss of this extraordinary man."

Pro Football Hall of Fame president and CEO David Baker said the organization would fly the flag at half-staff on Friday in honor of Rooney.

“The Pro Football of Fame family mourns the loss of an incredible and loving man," Baker said in a statement. "Ambassador Rooney epitomized all that is GREAT about this game that he and his family helped grow into an American institution. His impact on the game was profound.

Former coach Bill Cowher said in a tweet: "RIP Dan. My Mentor & friend. Thank you for your Guidance & Wisdom. I came a Young Coach & left a Better Man. Your spirit will live forever."

Current Steelers wide receiver Antonio Brown left a heartfelt message on Instagram that said, in part, "You looked at me as more than just another jersey number. One of the most genuine, and humble human beings I've had the pleasure of knowing. You motivated me not only to excel on the field but also in life. This season, the number 84 on my uniform will represent the 84 years you spent on this earth making an impact on the lives of others."

In his later years, Rooney became powerful in league circles on many levels, and is best known for the league’s effort to make the league’s coaching ranks more diverse and his appointment as ambassador of Ireland by President Obama.

This is how former coach Bill Cowher described him, according to the Pittsburgh Post-Gazette: “He was like a father, a friend, a mentor, a boss who inspired others around him. He was a people person and he never forgot where he came from. He epitomized Pittsburgh — hard working, humble, no-nonsense, tell it the way it is and never forget where he came from. That’s him, that’s Pittsburgh.”

The "Rooney Rule," created in 2003, required teams to interview minorities for head coaching vacancies and senior football operations jobs. The rule was expanded in 2016 to include women for executive openings.

"In the past, we've had some that were just token interviews," Rooney told USA TODAY Sports in May 2013. "They talked to someone on their staff for two minutes and said, 'Ok.' This hasn't been happening now. So I don't think you can get all excited over (backlash from) one year."

Seventeen minority head coaches were hired from 2003 through 2017, more than double the number that had been hired since the NFL’s founding in 1920.

There are currently eight minority coaches in the NFL, including Steelers coach Mike Tomlin.

Rooney, a supporter of President Obama’s 2008 presidential campaign, was appointed as the ambassador to Ireland in 2009 and held the post until 2012. Rooney had long been a supporter of Ireland, raising millions to support cultural and education efforts in the country.

Rooney’s father, Art Rooney Sr., purchased the Steelers in 1933, a year after Dan Rooney’s birth with, urban legend has it, with $2,500 in racetrack winnings. The Rooney family has long had business interests in horse and dog tracks, which led the Steelers to restructure its ownership structure to comply with NFL anti-gambling rules.

Rooney was elected to the Pro Football Hall of Fame in 2010.