The first government shutdown in 17 years is the result of Congress failing to pass a budget; without it, the government doesn't have the authority to spend money on anything but "essential" services. Sports are apparently not among them—the service academies have suspended all sporting events effective today.
The Department of Defense made the announcement earlier this afternoon—all intercollegiate events involving the U.S. Military Academy, Naval Academy, and Air Force Academy are off until further notice. The annual Navy-Air Force football game, which was to be nationally televised from Annapolis, is still up in the air: a decision will be made by noon on Thursday.
Up to half of government employees, and hundreds of thousands of civilian employees, could be furloughed without pay for the length of the impasse. This number includes much of the service academies' support staffs, who would be ineligible to travel during the shutdown and may not be allowed to work at all. Even some players could be affected: at Air Force, upperclassmen are considered government employees and would be subject to the travel ban.