The federal government has previously shut down 17 times in the past four decades. The longest shutdowns were:
• 1. December 16, 1995 to January 6, 1996, 21-day dispute between President Clinton and the Republican House over budget deficit projections.
• 2. September 30 to October 18, 1978, 18-day dispute over President Carter's veto of a bill funding a a nuclear-powered aircraft carrier and additional disputes over Medicaid funding for abortion.
• 3. September 30 to October 13, 1977, 12-day dispute between the House and Senate over Medicaid dollars for abortion.
• 4. September 30 to October 12, 1979, 11-day dispute between the Senate and House over pay raises for Congress and abortion spending.
• 5. September 30 to October 11, 1976, 10-day dispute between President Ford and Congress over social spending.
Prior to 1980, most government agencies kept operating without a budget. But in 1980 and 1981, Attorney General Benjamin R. Civiletti issued two opinions that more strictly interpreted the Antideficiency Act to limit what operations are "essential" and may continue without a budget
Source: A Brief History Of Federal Government Shutdown, Outside the Beltway. April 2011.