George Strait has been announced as the first headliner for the 2009 Summerfest concert series in Milwaukee, Wis. He will perform June 29 at the Marcus Amphitheatre. No other performers have been announced. Billed as the world's largest music festival, the event will be held June 25-July 5 from noon until midnight daily. Ticket prices and on-sale dates have not been announced. As previously reported, Strait will also perform at the Craven Country Jamboree in Regina, Saskatchewan, Canada, on July 12, as well as Cheyenne Frontier Days in Cheyenne, Wyo., on July 18.