Historical clue formulations

• Central points — 2024-07-16
• Centers — 2022-08-04
• Nexuses — 2020-12-30
• O'Hare and LAX — 2018-07-11
• Connection points — 2017-11-17
• Where many connections are made — 2016-11-06
• Nerve centers — 2016-08-06
• Centers of activity — 2015-11-25
• Central points — 2015-10-07
• O'Hare and Dallas/Fort Worth — 2015-08-09
• LAX, O'Hare and others — 2014-06-29
• Centers — 2014-05-27
• Car parts that have caps — 2014-01-27
• Centers of wheels — 2013-12-16
• Parts of cars with caps — 2007-11-26
• Centers — 2005-02-13
• Major airports — 2002-11-04
• Meccas — 2001-08-10
• Cores — 1996-11-02
• Primary intersections — 1995-05-24
• Centers — 1994-07-18
• Centers of activity — 1994-04-01