How it happened: Corey Crawford stopped all 30 St. Louis shots and the Blackhawks got a second-period goal from Bryan Bickell and a short-handed goal from Jonathan Toews in the third period to earn the victory.
Bickell tipped in a rebound on a shot that hit the post 4:31 into the second period, the first goal allowed by the Blues' Brian Elliott in 214 minutes.
In the third period, the Blackhawks increased the lead to 2-0 when Jonathan Toews won a face off to the left of Elliott and got the puck to Hossa, who fired a shot into the net for his 15th goal of the year. The goal came just 16 seconds after Duncan Keith was sent off the ice for tripping.
Player of the game: Crawford raised his record to 17-4-4 as he continues his battle with Ray Emery to see which of the Chicago goalies will emerge as the regular once the playoffs get underway.
What it means: Having clinched the division title with a win over Detroit on Friday night, the Blackhawks' next goal is to secure first place in the Western Conference. Sunday's win increased their lead over second-place Anaheim to nine points, 68-59. The Ducks lost to the Los Angeles Kings on Saturday night and do not play again until Wednesday night. Chicago has one game in hand, but will match the Ducks' 42 games played on Monday night.
The loss hurts the Blues, who are still fighting to secure a spot in the playoffs. They remained at 48 points, currently sixth in the Western Conference.
What's ahead: The Blackhawks will be back at United Center on Monday night, hosting the Dallas Stars. They have seven games remaining in this shortened regular season.