As of Monday, the federal government has been partially shut down for 16 days, making it tied for the third-longest shutdown in U.S. history.

The other shutdown that lasted 16 days took place from Oct. 1, 2013 to Oct. 17, 2013. There have been 21 government shutdowns since Congress began using the modern budgeting process in 1976. Some of them have lasted just a few days, or even a few hours — as was the case of the shutdown last February—and haven’t really affected government operations.

But when shutdowns take place during normal workdays, they mean that government functions largely grind to a halt and federal employees are furloughed or, if they’re deemed “essential,” forced to work without pay.

The government is supposed to be funded through an annual process that involves Congress passing 12 appropriations bills to fund all the different government agencies. If this process is not completed by the start of the new fiscal year on Oct. 1, the government partially or completely shuts down.

Congress can avoid a shutdown by passing continuing resolutions that let agencies keep spending at their current levels, but lawmakers don’t always reach a deal in time.

The current shutdown started on Dec. 22 after talks broke down between Congressional leaders and the White House. The officials failed to come to a compromise on a spending deal that President Donald Trump demanded include money for his wall on the U.S.-Mexico border.

Most of the government was already funded, so this is a partial shutdown, but it has affected nine federal departments as well as other agencies, totaling about 800,000 federal workers. More than half of those have been forced to work without pay throughout the shutdown, with the other half furloughed.

The weeks-long shutdown left some workers in a tough position over the holiday season, and has continued to affect millions of Americans as large chunks of the government have remained closed into January.

The only shutdowns that have lasted longer than the current one took place in 1978 and 1995-1996. The 1978 shutdown, during Jimmy Carter’s presidency, lasted 18 days. This shutdown took place after Carter vetoed public works legislation and a defense spending bill that included a nuclear-powered aircraft carrier because he considered them wasteful.

The grand record holder came when President Bill Clinton clashed with then-House Speaker Newt Gingrich over domestic spending cuts, and it lasted 21 days from Dec. 16, 1995 to Jan. 6, 1996. If the current shutdown extends until Saturday, it will tie the Clinton-era shutdown for the longest in American history.

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Write to Abigail Abrams at abigail.abrams@time.com.