The partial US government shutdown is tied for the longest ever as Trump border wall fight rages on

The partial U.S. government shutdown entered its 21st day Friday, tying the record for longest lapse in federal funding.

The dubious distinction comes on the same day hundreds of thousands of U.S. workers start to miss paychecks. About 800,000 federal employees are either furloughed or temporarily working without pay as the closure persists.

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Lawmakers have failed to fund nine departments, or about a quarter of the government, as President Donald Trump demands more than $5 billion to fund his proposed border wall. The president has threatened to veto legislation passed by the Democratic-held House to reopen the government temporarily, which has deterred the GOP-controlled Senate from passing it.

The funding lapse also has an economic cost. The lack of worker paychecks and the shutdown's potential effects on tax refunds, mortgage applications, food assistance programs and consumer sentiment could hit the U.S. economy to the tune of at least $2 billion a week, according to an estimate by Wells Fargo retail analysts. Meanwhile, S&P Global gave a "conservative" estimate that the closure had an economic effect of about $3.6 billion through Friday. The financial services company expects the shutdown to trim about 0.05 percent, or $1.2 billion, off quarterly GDP growth for each week that it goes on.

"If the partial government shutdown continues for two more weeks, our estimate of the total impact will be $6.0 billion, which would exceed the $5.7 billion in funding being requested to build a border wall," wrote Beth Ann Bovino, the U.S. chief economist for S&P Global Ratings.

The longest previous shutdown lasted three weeks during December 1995 and January 1996. It followed a budget spat between President Bill Clinton and House Speaker Newt Gingrich.

As it affects about a quarter of the government, the current shutdown disrupts fewer people than some previous funding lapses such as the 1995 closure. During other previous shutdowns, particularly in the 1970s, workers did not face furloughs.

Still, it could drag on much longer.

Talks to reopen the government crumbled this week. Trump on Thursday canceled his planned trip to the World Economic Forum in Switzerland later this month, signifying the closure could last for weeks more.

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