Mullen scored two more goals in his final 10 games to finish with 502 in 1,062 games with the St. Louis Blues, Calgary Flames, Penguins and Boston Bruins.
"I guess when you're the first to do anything it means something," Mullen said. "At the time it was the milestone I was going after. I knew it was a big one. It was one I struggled to get a little bit. Made it nicer and more of a relief than anything to get it over with."
Mullen left New York for Boston College in 1975, and never was drafted into the NHL. After graduating college, he signed with the St. Louis Blues in 1979 and started his professional career with the Salt Lake Golden Eagles in the Central Hockey League in 1979-80.
He reached the NHL in his third professional season, and had 59 points (25 goals, 34 assists) in 45 games with the Blues in 1981-82. He went on to score at least 40 goals seven times, topped by 51 with the Flames in 1988-89.
When Mullen reached the NHL, he was the rare U.S.-born star. When he retired after the 1996-97 season, the League landscape had changed markedly, with American players like Mike Modano, Jeremy Roenick and Keith Tkachuk considered among the game's best.
"I think there was a little extra pressure on us at that time," Mullen said of his early days in the League. "Wasn't a whole lot of Americans that had gone through the NHL when I first came into the League. I was kind of like with that [1980] Olympic team. They were coming in and I came in just after them."
Mullen finished his NHL career with 1,063 points, and was the first U.S.-born player to reach 1,000 points.