What this means: 4,000 FAA employees and 70,000 airport construction workers were immediately furloughed, the latter due to stop-work orders issued by the FAA to construction contractors. In addition to the furloughed workers, at least 40 safety inspectors are expected to continue working without pay, even covering their own travel expenses. Because Congress adjourned without passing funding, the shutdown will continue through September, delaying both airport construction and renovation projects intended to allow greater traffic, and an overhaul of the air traffic control system which promises to revolutionize air travel. It will also deny the government over $1 billion in revenue from ticket taxes, $200 million of which has been lost already. This savings is not being passed on to consumers, however, as airlines immediately increased fares by the same amount as the tax.

What caused it: Since a multi-year reauthorization passed in September 2007, the FAA has been operating on short-term funding increases. The House and Senate both passed long-term reauthorizations, but the two bills were different. Short-term extensions to funding were set to expire July 23. However, the short-term extension proposed by House Transportation chair John Mica to maintain funding while Congress reconciled the long-term bills included a limited version of one of the provisions in the House's long-term bill drawing Senate ire. The Senate refused to pass the short-term bill, causing the shutdown. The administration, including Transportation Secretary Ray LaHood and President Obama himself, urged the Senate to pass Mica's bill this week, even with these provisions, to end the shutdown, but Senate Majority Leader Harry Reid refused.

What the bills say: The provision Mica added to the short-term bill causing the shutdown would cut funding for the Essential Air Service program, which provides funding to rural airports that otherwise cannot sustain themselves. The long-term reauthorization passed by the House phases out funding completely for EAS. Also in that reauthorization was a provision that would reverse a regulator's ruling that airlines can unionize if an election is held and a majority of ballots favor a union — the same procedure as in most workplaces. Previously, those not voting in airline unionization elections were counted as "no" votes, an unusual practice the House bill sought to restore. The House bill would also allow more long-distance flights to Ronald Reagan National Airport, a provision opposed by Maryland and Virginia representatives who want to protect other airports’ business and avoid higher noise levels for their constituents. The Senate bill does not phase out EAS funding or reverse the union ruling, and increases flights to Reagan by a smaller amount.

What happens now: Harry Reid has said that, because Congress is in pro forma session for the recess, the House and Senate could still pass a clean funding increase. Barring that, the FAA will remain shut down for the August recess. Safety inspectors will work without pay, assuming they do not simply quit, and about 74,000 workers will be at least temporarily unemployed.