US federal employees have received pay stubs with nothing but zeros on them as the effects of the government shutdown hit home, deepening anxieties about mortgage payments and unpaid bills.
All told, an estimated 800,000 government workers missed their paychecks on Friday for the first time since the shutdown began.
Employees posted pictures of the pay statements on Twitter and vented their frustration as the standoff over President Donald Trump's demand for $US5.7 billion for a border wall entered its 21st day.
This weekend, it will become the longest shutdown in US history.

Air traffic controller Bill Striffler's pay check is full of zeros. Source: AAP
"I saw the zeros in my pay stub today, and it's a combination of reality setting in and just sadness," air traffic controller Josh Maria told The Associated Press after tweeting a screenshot of his paystub.
"We're America. We can do better than this."
The missed paychecks were just one sign of the mounting toll the shutdown is taking on Americans' daily lives.
The Miami airport is closing a terminal this weekend because security screeners have been calling in sick at twice the normal rate.

Source: AAP
Homebuyers are experiencing delays in getting their loans.
Roughly 420,000 federal employees were deemed essential and are working unpaid. An additional 380,000 are staying home without pay. While furloughed federal workers have been given back pay in previous shutdowns, there is no guarantee that will happen this time.
Workers are turning to Uber, Lyft and other side gigs to pick up some money in the meantime.
Ellen Jackson, a Transportation Security Administration officer based in Las Vegas, is driving full time for a ride-share company to get by. The 59-year-old is planning to retire in April.
"I don't want to borrow any money," said Jackson, an Air Force veteran who said she makes about $US38,000 ($A52,600) a year as a TSA officer. "I don't want to get into a deeper hole."
Fellow Las Vegas-based TSA agent Julia Peters applied for food stamps on Thursday and was approved. She said five of the eight other applicants at the benefits office were also TSA workers.
In Falls Church, Virginia, outside Washington, a school district held a hiring fair for furloughed federal employees interested in working as substitute teachers.
Gerri French, who works for the Department of Agriculture's Food Inspection Service and has been furloughed along with her husband, liked the sound of substitute teaching. "I think it's a really great school system, and this would be a great opportunity," French said.
Chris George, 48, of Hemet, California, has picked up work as a handyman, turned to a crowdfunding site to raise cash and started driving at Lyft after being furloughed from his job as a forestry technician supervisor for the US Forest Service.
But the side gigs aren't making much difference, and he has been trying to work with his mortgage company to avoid missing a payment.
"Here we are, Day 21, and all three parties cannot even negotiate like adults," he said, describing government workers like him as "being pawns for an agenda of a wall. You're not going to put a wall across the Rio Grande, I'm sorry."