There have been 21 federal government shutdowns in the United States over the past 50 years, with 14 occurring since 1980. Shutdowns have varied in length, with the longest lasting 35 days from December 22, 2018, to January 25, 2019, during President Trump's administration. Earlier significant shutdowns include those in 1995-1996 under President Clinton (21 days) and in 2013 under President Obama (16 days). Shutdowns result from funding legislation lapses and political disagreements between Congress and the President, affecting government operations and resulting in furloughs of federal employees.

Summary of notable shutdowns:

• 2018-2019 (Trump): 35 days, longest in U.S. history
• 1995-1996 (Clinton): 21 days
• 2013 (Obama): 16 days
• Several shorter shutdowns occurred mainly from the 1980s onward

Shutdowns happen when Congress fails to pass funding bills before the new fiscal year starts, leading to curtailed government services and furloughs.