A government shutdown happens in the United States when Congress fails to enact sufficient appropriation bills or continuing resolutions to support federal government operations and agencies, or when the President refuses to sign such legislation.¹⁾

In such instances, the current interpretation of the Antideficiency Act authorizes the federal government to initiate a “shutdown” of the impacted operations, which includes furloughing non-essential staff and reducing agency activities and services.²⁾

Essential staff must continue to work without compensation until the government reopens, at which point they may be eligible for back pay. TSA agents and medical personnel from Veterans Hospitals may be among these staff.³⁾

Since the present budget and appropriations process was established in 1976, there have been 22 funding gaps, 10 of which have resulted in government employees being furloughed.⁴⁾

Prior to 1990, budget shortages did not necessarily result in government shutdowns, but after 1990, all financial gaps have resulted in government shutdowns.⁵⁾

There were eight shutdowns lasting four days or fewer during Ronald Reagan's presidency. Arguments over the fairness doctrine, a welfare package, a water package, a crime fighting package, foreign assistance cutbacks, MX missile financing, essential expenditure legislation, and defense cuts were among the reasons given.⁶⁾

During the George H. W. Bush administration, a financial shortage resulted in a weekend closure in 1990.⁷⁾

During Bill Clinton's presidency, there were two full government shutdowns, lasting five and 21 days, respectively, due to disagreements about whether to eliminate government services.⁸⁾

During Barack Obama's presidency, a 16-day government shutdown occurred in October 2013 due to Democrats and Republicans failing to reach an agreement on the Patient Protection and Affordable Care Act, generally known as Obamacare.⁹⁾

During the Trump administration, there have been three budget shortfalls. In January 2018, there was a three-day stoppage. A budget gap that occurred overnight on February 9, 2018, but did not result in furloughs, as well as an ongoing shutdown that began in December 2018, over planned financing for a US-Mexico border wall.¹⁰⁾

Government shutdowns have the impact of interrupting government services as well as raising government expenditures owing to lost labor.¹¹⁾

During the 2013 closure, the financial ratings firm Standard & Poor's reported on October 16 that the shutdown had “to date knocked $24 billion out of the economy” and “shaved at least 0.6 percent off annualized fourth-quarter 2013 GDP growth”.¹²⁾

The United States Congress has sole power of the purse and responsibility for appropriating government funds under the separation of powers established by the United States Constitution. Appropriations, like other measures, must be approved by both the House of Representatives and the Senate. They are sent to the President of the United States when both chambers have passed a final version. The legislation become law if the President signs them. If the President instead vetoes them, they return to Congress, where the veto can be overcome (in rare cases) by a two-thirds majority of both chambers.¹³⁾

Government shutdowns often occur when the President and one or both chambers of Congress are unable to reach an agreement on budget allocations before the current fiscal cycle ends. Many government agencies initially continued to operate during shutdowns, while reducing all non-essential operations and commitments.¹⁴⁾