For 2016, RallyX Nationals will be returning to Indianola, IA for its 10th anniversary. This site held up very well last year and if it's drier this year, I will be thrilled.
More details here: http://www.scca.com/events/1981848-2016-scca-rallycross-national-championship
More details here: http://www.scca.com/events/1981848-2016-scca-rallycross-national-championship