Simple travel booking step could have saved American travelers more than $10 billion in 2009.

When travelers book their hotel and flight as a "package" - defined as booking them simultaneously on Expedia.com - travelers can save up to $450 per transaction compared to the cost of booking the same components separately.

If all U.S .travelers who required a flight and a hotel had saved even just $100 by booking their flight and hotel together, they would have collectively saved more than $10 billion in 2009 alone. Expedia customers worldwide saved $410 million booking their flights and hotels at the same time last year, compared to what they would have paid had they booked the components separately.

"There's no trick, no special stipulations, no mail-in rebates, nothing required of travelers other than to book their flight and their hotel at the same time," said Tim MacDonald, senior vice president and general manager, Expedia.com. "Packages are the easiest money saver available to modern travelers. Book a hotel and flight together, and you could save big. It's that simple."

Expedia.com customers can typically expect to save up to $450 per trip, but the company is currently running a special packages promotion that promises to yield even greater savings than normal, with more than 500 destinations to choose from and thousands of deals available. To receive this extra discount, travelers should book their flight and hotel together through March 3 and travel by April 30, 2010.

"Package" bookings are easily confused with pre-packaged deals, in which travelers are offered a limited set of bundled properties and flights. Despite the confusing terminology, packages are a straightforward concept. Airlines and hotels have empty seats and rooms. When travelers book them at the same time, Expedia can offer prices that airlines and hotels won't reveal separately.

"We actually kicked around some ideas for renaming packages, to try and eliminate the confusion," Tim MacDonald added. "'Flotels' was considered, but it sounded like we were trying to rename cruise ships. 'Hotights' didn't make the cut, and neither did 'simulbookings.' We're obviously open to suggestions here. The name is less important than the point: if you book your flight and hotel at the same time, you can save money. We can't say that often enough, but we plan to try."