Wainwright hit the 20-win mark for the second time while matching his career-high for victories, and the Cardinals moved a step closer toward their second straight division title.
They remained 2 1/2 games ahead of Pittsburgh in the NL Central with five to play with the Pirates beating Atlanta 1-0. St. Louis clinched its fourth straight playoff appearance on Sunday.
Wainwright (20-9) won his fifth straight start and made it look easy, striking out eight and walking one.
The only other time Wainwright won 20 was in 2010, and that year, victory No. 20 also came at Wrigley Field.
He got plenty of support in this one, with the Cardinals pounding Travis Wood (8-13) for seven runs and eight hits over five innings.
They scored four in the fourth and three in the fifth on the way to their eighth win in 10 games.
Matt Holliday had two hits and scored two runs. He also drove in one.
Holliday also had a run-scoring double to left and Yadier Molina singled in a run in that inning, and the Cardinals broke it open in the fifth.
Matt Carpenter led off that inning with a walk and was ruled safe at second tagging on Randal Grichuk's fly to center following a replay review. He scored on Holliday's bloop single to right, and Adams capped the rally with a two-run single to make it 7-0.
Cardinals: Adams and Carpenter returned to the lineup after missing two games because of a stomach virus that's been battering the team. Nearly half the Cardinals' players and coaches have been affected by it in recent days. Assistant batting coach David Bell and pitcher Marco Gonzales were not with the team Monday because of the virus. "I've never seen (a virus) hit that quick or that bad," manager Mike Matheny said. "This is the time of the season when guys aren't feeling good, but not like that. That was a bad deal."
Cubs: RF Jorge Soler was back in the Cubs' lineup after leaving Saturday's game against the Dodgers as a precaution due to wet conditions. He had a scheduled day off on Sunday.
RHP Shelby Miller (10-9, 3.68 ERA) looks to stay on a roll for St. Louis, as the Cardinals continue their three-game series against the Cubs. He is 2-0 with a 0.69 ERA in four starts in September. RHP Kyle Hendricks (7-2, 2.28) starts for Chicago.
Link to box score: St. Louis (88-69) 8 at Chicago (69-88) 0
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