The Giants had not won a regular-season series on the Reds' home field since August 2009, losing 10 of their last 11 there before this series began.
"It's been a tough park for us," San Francisco manager Bruce Bochy admitted. "We've played some of our worst baseball here. Our first game here was one of our ugliest. But this turned out to be a nice series and a great road trip."
The Giants finished with a 5-2 record on their trip through St. Louis and Cincinnati. San Francisco takes baseball's best record and the biggest advantage of any division leader into a 10-game homestand that begins Friday. The Giants have not lost a series since May 5-7 in Pittsburgh.
"We're pretty consistent," Crawford said. "It doesn't matter where we're playing right now."
Bumgarner (8-3), National League Pitcher of the Month in May, shut down the Reds after a stressful first inning. He finished his eight-inning workshift by retiring 23 of the last 24 he faced.
"He pitched like it was still May," Crawford said.
The 24-year-old left-hander has a 1.91 ERA over his last seven starts. He gave up hits to two of the first three batters he faced, including Todd Frazier's solo home run, before settling in.
"He was hitting all his spots," Reds leadoff hitter Billy Hamilton said of Bumgarner. "Of course, it could have been both ways; we could have hit better. But I feel like he did a great job today of mixing up his pitches and hitting his spots."
"What a job he did," Bochy said.
Bumgarner even gave Reds fans something to cheer about. When Cincinnati reliever J.J. Hoover got two strikes on Bumgarner in the eighth inning, what had been a quiet crowd came to its feet. Hoover eventually fanned Bumgarner, the 11th strikeout of the day for Cincinnati pitchers -- the number needed for a local restaurant chain to give out free pizza to ticketholders.
The only other occasion for Cincinnati fans to cheer came during the first inning.
Right fielder Hunter Pence sprinted into the gap to rob the game's first hitter, Hamilton, of what would likely have been a double. Pence was helpless to assist Bumgarner on the next pitch, however, as Frazier belted it into the right-field seats to open the scoring.
Frazier's 12th homer of the season was the first Bumgarner had given up to any current Reds hitter. Frazier added a third-inning single, but that was it for the Cincinnati order. Bumgarner and reliever George Kontos did not allow any of the last 19 batters to reach.
"We played one of our best ballgames defensively," Bochy said.
Crawford was stuck in a 4-for-32 skid (.125) when he came to bat against Mike Leake (3-5) in the fourth inning. San Francisco's shortstop took a mighty cut at Leake's first-pitch curve, driving the ball over the fence and six rows into the right-center stands. Crawford's seventh homer of the season extended a 2-1 Giants lead to 5-1.
Crawford then demonstrated highlights on the defensive side, going deep in the hole to rob Cincinnati's Devin Mesoraco and Chris Heisey of potential hits during the next half-inning. The Giants had been charged with seven errors during the first two games of the series, but played seamless defense Thursday.
"When your pitcher is pounding the strike zone and pitching to contact, it keeps the infielders on their toes," Bochy said.
Morse had given the visitors a 2-1 lead in the second inning with a two-run homer into the upper deck in left field, his 13th.
Pablo Sandoval, who had a 12-game hit streak snapped Tuesday, was 3-for-5 and scored two runs.