This is what some federal workers' pay stubs look like today
(CNN) -- The partial government shutdown is three weeks old, and it's gone on long enough for some of the 800,000 federal employees impacted to start missing pay.
This weekend is the first time that many of them are receiving paychecks with no money.
Take, for instance, William Striffler, an air traffic controller at Newark Liberty International Airport in New Jersey.
He gave CNN permission to use this image of his pay stub. The amount listed under "net pay?" $0.00.
Air traffic controllers are just a small fraction of the overall federal workforce that's been impacted by the shutdown.
Earlier Thursday, a group representing them were cosignatories on a letter to President Donald Trump, House Speaker Nancy Pelosi and Senate Majority Leader Mitch McConnell, appealing for the government to be reopened.
"As the shutdown persists, excepted air traffic controllers and workers in technical operations, who operate and maintain safety-critical navigational aids, surveillance, and communications equipment, are performing highly skilled and safety-critical services without pay," they write, while predicting the overall impact of the shutdown will make it harder to recruit aviation professionals in the future.
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