Tickets go on sale Monday (April 26) to the general public for the Eagles/Dixie Chicks' June 15 concert at Hersheypark Stadium in Hershey, Pa. A presale for American Express cardholders is already underway. According to the Washington Post, the Eagles' June 15 headlining concert at Nationals Park in Washington, D.C., was canceled because of scheduling conflicts. According to The Patriot-News newspaper in Harrisburg, Pa., Keith Urban will be performing at the concert in Hershey, although the date was not listed on the tour page of his official Web site concert as of late Wednesday afternoon (April 21). The Eagles and the Dixie Chicks are scheduled to perform eight stadium shows together in June. Urban will be appearing on several of those dates.