Historical clue formulations

• Ill. neighbor — 2020-12-17
• Neighbor of Ill. — 2020-03-07
• Where the Ringling Bros. circus began: Abbr. — 2018-02-07
• State in which "That '70s Show" was set: Abbr. — 2015-06-19
• Land O' Lakes land: Abbr. — 2015-06-13
• Badger's home: Abbr. — 2014-06-10
• Lake Michigan borderer: Abbr. — 2013-04-24
• Mich./Minn. separator — 2012-10-23
• Great Lakes state: Abbr. — 2012-07-27
• It borders two Great Lakes: Abbr. — 2011-04-06
• Mich. neighbor — 2010-05-27
• State known for its cheese: Abbr. — 2007-07-02
• Mich. neighbor — 2005-11-12
• Madison's home: Abbr. — 2002-08-11
• Ill. neighbor — 1998-11-18
• Minn. neighbor — 1996-02-11