According to a Congressional Research Service Report entitled Federal Funding Gaps: A Brief Overview by James V. Saturn, there have been 18 funding gaps since fiscal year 1971. Almost all of the funding gaps occurred between fiscal years 1977 and 1995. During this 19-fiscal-year period, 15 funding gaps occurred. Multiple funding gaps occurred during a single fiscal year in four instances: (1) three gaps covering a total of 28 days in fiscal year 1978, (2) two gaps covering a total of four days in fiscal year 1983, (3) two gaps covering a total of three days in fiscal year 1985, and (4) two gaps covering a total of 26 days in fiscal year 1996.
Brooklyn Law School Library has in its electronic collection The Government Shutdown of 2013: Perspective and Analysis by Rosanne C. Lundy. According to the description “When federal agencies and programs lack appropriated funding, they experience a funding gap. Under the Anti-Deficiency Act, they must cease operations, except in certain emergency situations or when law authorizes continued activity. Failure of the President and Congress to reach agreement on interim or full-year funding measures occasionally has caused government shutdowns. Government shutdowns have necessitated furloughs of several hundred thousand federal employees, required cessation or reduction of many government activities, and affected numerous sectors of the economy. This book discusses the causes, processes, and effects of federal government shutdowns; economic activity during the government shutdown and debt limit brinkmanship; impacts and costs of the October 2013 federal government shutdown; a brief overview of federal funding gaps; and operations of the Department of Defense during a lapse in appropriations.”