Over the last five decades, there have been 21 federal shutdowns: 2019: Under Trump. Lasted 35 days and cost the economy about $3 billion, equal to 0.02% of GDP, according to the Congressional Budget Office. USA TODAY's Michael Collins and Olivia Munson, Reuters contributed to the reporting of this story.

When would a federal shutdown start? Which parts of the government would shut down? Will payments to Social Security recipients be affected?

When the government shuts down, major nonessential services cease operation, meaning many federal employees may go without pay.

Another government shutdown is looming ever closer as Congress continues to race to fund the government before the weekend.