Originally Posted by westofyou
Until recently... in most of our lifetimes.
The 1880's big rivals
The 1920's Rivals
The late 30's early 40's rivals
Early to mid 60's rivals.
Division play and Augie Busch's insistence that he be in the same division as the Cubs (EAST though both are west of Cincinnati) created the world that we recall as being recent.
The Reds, from a Cardinals fan perspective, did not become a heated rival with the Cardinals until 2010ish. Prior to that, it's always been a team that we just played without any real angst towards it. Until 2010, they were on the low end of the rival scale, at least in Cardinals fans eyes. That might sound smug but it's true.