The sequester threat dates back to August 2011 when Democrats and Republicans were battling over the amount the federal government could legally borrow to pay its bills.
Republicans didn't want to raise the debt ceiling unless Democrats agreed to budget cuts. Democrats didn't want to cut.
As a compromise, Congress came up with a package of cuts that would go into effect if a bipartisan committee couldn't come up with a better deal: $850 billion would be subtracted from the budgets of dozens of federal agencies over 10 years, and half of it would come out of the military.
"The idea is that Republicans would hate defense cuts and Democrats would hate non-defense cuts," says Alan J. Auerbach, a University of California Berkeley professor of economics and law. "So the committee would come up with an agreement. But the committee didn't come up with an agreement."
The cuts were originally scheduled for Jan. 1, but the two sides agreed to push the deadline back to March 1 in hopes of working something out. They still haven't reached a deal.
Democrats are still holding out for tax increases to make the cuts less severe, and Republicans are determined not to raise taxes, the New York Times reports.
Auerbach is still betting that the two sides will reach a deal to avoid the cuts. "They were designed to be unpleasant and force and agreement, and I think they will do that," he says.
What if they don't?
It's not a pretty picture. The economy is still sluggish, and less federal spending means it will take even longer to pick up speed, says Auerbach.
To be sure, some cuts may be necessary, he says. The government has been spending more than it takes in, and that's not good for the economy in the long term. But the biggest increase has been in entitlement programs like Social Security and Medicare, and these are exempted from the sequestration cuts.
"If I could design policy, I would put in place a variety of structural reforms to entitlement programs and phase them in over time," Auerbach says. By "structural reforms" he means careful cuts, like for example raising the age when people become eligible for benefits, as opposed to suddenly trimming a percentage from everyone's Social Security check. He'd also increase taxes over time.
But he wouldn't do any of that right away, because he thinks the economy is too weak right now.
Levy agrees with estimates he's seen that the cuts could trim about half a percentage point from the national gross national product, and thinks California would suffer that proportionally.
In most respects, California would have a similar experience to the rest of the country.
The most immediate jolt would come if LaHood follows through on his threat to furlough air traffic controllers and shut down 100 air traffic control towers.
National parks could shorten hours. Doctors could lose 2 percent of their Medicare payments. Millions of dollars could evaporate from school districts.
Levy thinks the most serious effect would be the long-term consequence of reductions in research money from the National Institutes of Health, the National Science Foundation, universities and other institutions and other programs that lead to future inventions -- "the kind of things that support the venture capital economy in California."