In U.S. politics, a government shutdown is a situation in which Congress fails to pass authorization for sufficient funds for government operations. Typically, the government stops providing all but "essential" services at first, but since
Congress must authorize all expenditures, there is no law protecting any government service from stoppage. Federal services that may continue for a time after a shutdown include the National Weather Service and its parent agencies, medical services at federal facilities, armed forces, air traffic management, and corrections (the penal system).
During the Ford and Carter administrations, there were 6 partial government shutdowns that affected only the departments of Labor and Health, Education, and Welfare. These partial shutdowns lasted from 8 to 18 days and the primary issue of dispute was federal funding for abortion. During the Reagan administration, there were 8 full government shutdowns that lasted only 1 to 3 days apiece, primarily over the issue of the United States budget deficit.
There was a similar 4-day shutdown during the first Bush administration.
During the Clinton administration, after conservatives made massive congressional gains in the 1994 Republican
Revolution, there were two full government shutdowns lasting 5 and 21 days apiece, the second of which was by far the longest of its kind to that date. The primary issue was again the United States budget deficit.
The United States federal government shutdown of 2013 is ongoing, having begun on 1 October 2013. The primary issue of dispute between the Republican-controlled House of Representatives and the Democrat-controlled Senate (the latter supported by President Obama) is the Republicans' desire to delay implementation of the Affordable Care Act*.
*http://en.wikipedia.org/wiki/Government_shutdown_in_the_United_States