The Mariners history with the Oakland Coliseum is a long one.
When the A’s moved to Oakland from Kansas City after the 1967 season, senator Stuart Symington wanted another team in KC so badly that he threatened MLB’s anti-trust legislation. His threat worked, and MLB awarded KC a new franchise in the next round of expansion. And at the same time it offered one to the emerald city of Seattle. That team was the Pilots, who, of course, fled to Milwaukee after just one year.
But Seattleites wanted an MLB team so badly, that they broke ground on the Kingdome without either an MLB or NFL team.