Tom Kelly, who won in 1991, is the only other Minnesota manager to win the award.
Black edged Cincinnati's Dusty Baker by one point in winning the National League manager of the year award.
The Padres finished 90-72 and in second place behind the San Francisco Giants in the NL West after being a consensus pick to finish last in the division. San Diego led the division much of the season despite fielding the second-lowest paid lineup in baseball.
He joins Bruce Bochy, now the manager of the Giants, as the only Padres leader to be manager of the year. Bochy won in San Diego in 1996.
The awards are decided on a vote of members of the Baseball Writers Association of America, with a first-place mention with five points, a second-place vote three and one point for a third-place vote.
Black was first on 16 of the 32 National League ballots and took seven seconds and three thirds for 104 points. Baker was first on 13 ballots, second on 12 and third on two others for 103 points. Bochy (30 points) was third.
Gardenhire was a more clear-cut winner, taking 16 of the 28 AL first-place votes while he was second on eight and third on four for 108 points. Texas Manager Ron Washington, who got his team to the World Series for the first time, was second with 10 first-place votes and 81 total points.
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