Steen and Perron scored power-play goals, Halek stopped 33 shots, and the playoff-bound Blues beat the Dallas Stars 3-2 on Saturday night in the regular-season finale for both teams.
Kris Russell added an even-strength goal for the Central Division-champion Blues, who snapped a season-worst four-game losing streak (0-2-2) to finish with 109 points -- the most since they had 114 in 1999-2000.
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St. Louis will await the results of the Edmonton-Vancouver and Los Angeles-San Jose games to learn whether it will earn the No. 1 seed in the Western Conference. The Canucks came into Saturday's games with 109 points and will win the Presidents Trophy and the West's top seed with a win over the Oilers.
The Blues became a conference power after Hitchcock took over behind the bench early in the season, leading the team to 43 wins in the final 69 games.
"All of us are excited," Hitchcock said. "We're really proud of what's going on here. Who knows? This is the new season. Your best players have to be your best players and others have to step up."
Russell opened the scoring with 8:54 left in the second period on a shot deflected off Stars defenseman Philip Larsen's stick. The puck popped into the air, fluttering over Stars goaltender Richard Bachman's right shoulder and into the net for Russell's sixth of the season.
Steen notched his 21st of the season to give St. Louis a two-goal margin at 7:54 of the third, and the Blues survived goals from Stars rookies Ryan Garbutt and Larsen in the game's final 11 minutes.
Now the Blues can turn their full attention to the playoffs.
"We made the playoffs. That was our goal," Russell said. "Now we have to build off our regular season. We have to make sure we come prepared."
The Stars ended their season with 89 points, losing their final five games. Dallas was eliminated from playoff contention with Thursday night's 2-0 defeat at Nashville.
Dallas, which will miss the playoffs for a franchise-record fourth straight season, went with a lineup that featured seven rookies including Bachman, who started instead of Kari Lehtonen and finished with 32 saves.
A makeshift group of newcomers and veterans caused some disjointed play by the Stars.
"It was a different game, but I thought we competed hard, and I thought some of our young guys showed pretty well," Stars coach Glen Gulutzan said.
The Stars had risen to the top of the Pacific Division with a 10-0-1 run through March 13, but they drifted out of the top eight with a 3-9-0 finish.
Hitchcock went with his top-end players rather than protecting them from injuries in an effort to stop the late-season skid.
He didn't like the way his team got started when St. Louis was whistled for three minor penalties in the game's opening 10 minutes. But the Stars generated only one shot on goal in the three chances. Dallas' power play started the night tied for last in the NHL (13.8 percent).
As the game wore on, the Blues raised their level against a rookie-laden opponent.
"I thought we started slow, got into penalty trouble, had an 18-minute span where we were really good, then I thought we were really good in the third period," Hitchcock said. "We could have scored five or six goals. I was really, really happy."