As US shutdown starts to bite, how much could it hit economy?

Michael Galletly, who works for the Department of Agriculture in Utah, sat down with his wife last week, combing through bills and spending for more than two hours to strategise how to make it through the government shutdown.

The outlook - uncertain.

"I could make it two months, maybe three lean, very lean months," said Mr Galletly, an IT management specialist, who is also president of American Federation of Government Employees Local 4016. "But I don't know how long this thing is going to go."

The impasse has already snarled travel, delayed government approvals for permits and loans and shuttered some museums.

Now as millions of federal workers across the government start to miss paycheques this week and respond by curtailing spending, analysts say the impact will start to reverberate more widely.