This history is relatively young.
Trades between St. Louis Cardinals & Seattle Mariners
November 9, 1979: The Seattle Mariners purchased Dan O’Brien from the St. Louis Cardinals.
June 7, 1979: The Seattle Mariners purchased Rob Dressler from the St. Louis Cardinals.
June 26, 1978: The Seattle Mariners traded Jose Baez to the St. Louis Cardinals for a player to be named later. TheSt. Louis Cardinals sent Mike Potter (October 27, 1978) to the Seattle Mariners to complete the trade.