The U.S. government has experienced 21 federal shutdowns over the last 50 years, with the first official shutdowns occurring around 1980. Shutdowns happen when Congress fails to pass the annual appropriations bills or a continuing resolution to fund government operations before the fiscal year deadline, leading to a lapse in funding. Shutdowns have varied in frequency and duration, with only six shutdowns occurring since 1990. The longest shutdown lasted 35 days during December 2018 to January 2019, primarily due to a political stalemate over border wall funding. Shutdowns are not on a fixed schedule but arise from budgetary disputes between Congress and the President. They have become rarer in recent years but remain a risk where political divisions block agreement on spending. Generally, shutdowns happen when an impasse is reached over the federal budget by the fiscal year's start on October 1, but the timing depends entirely on negotiations. Since 1990, shutdowns have occurred sporadically and vary from brief partial shutdowns to multi-week full shutdowns.
In summary, the government does not shut down on a regular schedule, but shutdowns occur irregularly when Congress fails to agree on funding before the fiscal year begins, happening about 21 times in 50 years with significant variation in frequency and length.
