City of Valparaiso Trick-or-Treat Time Is Set By: City of Valparaiso Last Updated: September 15, 2010 facebook twitter linkedin email print Mayor Costas has set the date for City of Valparaiso’s Trick-or-Treat time. Trick-or-Treat will take place from 5:00-7:00pm on October 31, 2010. Any questions, please contact city hall at 219-462-1161.