There was an old clerk of Columbus
Who wearied of totalling numbus,
    So he moved to East Lansing
    And spent his time dancing
Maxixes, merengues, and rhumbus.
--Col. G. L. Sicherman
Calling Ideas for June 17, 2012

June is:

National Accordian Awareness Month
National Accordion Awareness Month was established in 1989 to promote the accordion, help spread the word about the resurgence in popularity in the accordion and to educate people about the accordion. Here's some info.

I'm sure there are bunches of (old) square dance records that feature the accordian. I tend to associate MacGregor with accordian arrangements.