On September 18, 1968, less than 24 hours after being no-hit by San Francisco Giants hurler Gaylord Perry, Ray Washburn returned the favor by no-hitting the Giants in a 2-0 Cardinals victory. It was the first time in the history of the game that two teams no-hit each other on back-to-back days. Washburn, a 30 year old seasoned veteran worked around two first inning walks by striking out Willie Mays and Dick Dietz to get out of the jam. It was the only time in the game that Washburn allowed a man to reach second base, he did walk three more men while striking out seven men on his way to becoming the fifth pitcher in the history of the organization to record a no-hitter. Washburn was provided with all the run support he would need with an rbi double of the bat of Mike Shannon in the seventh, then Curt Flood picked up a ribbie with a single in the eighth for a little insurance. It took 138 pitches to complete the no-hit bid, he recorded the last three outs of the game with a pair of groundouts by Ron Hunt and Willie Mays before he got Willie McCovey to hit a soft liner to Curt Flood to complete the feat, it was only the second ball of the day that left the infield. The day before Perry outdueled Bob Gibson and needed just 101 pitches to complete his no-hitter. Gibby scattered 4 hits with one of those being a first inning homer off the bat of Ron Hunt that the Cardinals couldn't get past as Perry shut down the Cardinals lineup. While the Giants were flying high after Perry's no-hitter, Washburn brought them right back down to earth as he matched the performance with a no-hitter of his own.
Only one other time had there been no-hitters tossed at a ballpark in consecutive days. It happened in 1917 when the St. Louis Browns no-hit the Chicago White Sox at Sportsman's Park in St. Louis, but it happened over three games. The first no-no was tossed by Ed Koob on May 5th then the second no-no was tossed by Robert Groom in the second game of a doubleheader the next day.
Here's the box score from Washburn's no-no: http://www.baseball-reference.com/boxes/SFN/SFN196809180.shtml