Related Clues:

• Reagan-___
• One billion years, geologically
• Stat that's good when it's low
• Humongous span
• Annoying wait, facetiously
• A good one in the NL is low
• Untold eras
• Clinton __
• Inconceivable stretch
• Timeline portion
• Cold war ___
• The sixties, for one
• It's low for aces: Abbr.
• Memorable time period
• Pitcher's stat, for short