 PLoP has been held in the U.S.A. since 1994.Until 2004 it was held annually at Allerton Park in Monticello, Illinois, a property of the University of Illinois at Urbana Champaign.Since then, its location has alternated between Allerton park and being co-located with OOPSLA, a large computer science conference, with the Agile Conference in 2009, and with PUARL in 2018.