A government shutdown occurs when the legislative branch does not pass key bills which fund or authorize the operations of the executive branch, resulting in the cessation of some or all operations of a government. In the United States, government shutdowns have occurred periodically since 1980, and are the result of failure to pass appropriations bills before the previous ones expire. Under the Antideficiency Act, federal agencies cannot spend or obligate any money without an appropriation (or other approval) from Congress. When Congress fails to enact the 12 annual appropriation bills, federal agencies must cease all non-essential functions until Congress acts. Shutdowns can be disruptive, leading to delays in processing applications for passports, small business loans, or government benefits; shuttered visitor centers and bathrooms at national parks; fewer food-safety inspections; and various inconveniences. During a government shutdown, processing Federal Housing Administration (FHA) loans may be delayed due to reduced staffing. However, the Department of Housing and Urban Development (HUD), which oversees the FHA, maintains a limited staff to continue loan processing and other essential government services continue to operate during a shutdown, either because they are excepted from furloughs to ensure public safety and welfare or are funded outside of annual appropriations (such as mandatory spending programs or self-funded programs) . The longer a shutdown lasts, the more programs are put at risk—as contingency funds run dry, grants expire, and some states and local governments may have to step in to keep programs running.