An estimated 1.5 million passengers flew in and out of Chicago's two airports over the Labor Day weekend -- -- roughly 100,000 fewer than over Labor Day 2006, The Chicago Tribune reported.

Chicago is seen as an industry bellwether since it is a major travel hub dominated by the two largest U.S. carriers, AMR Corp.'s American Airlines Inc. and UAL Corp.'s United Air Lines Inc., as well as leading low-cost carrier Southwest Airlines Co. (NYSE:UV), the newspaper said.

Less competition for seats means slashed fares for people willing to travel during off-peak periods this fall, travel executives said.

"The world will be on sale," BestFares.com Chief Executive Officer Tom Parsons told the Tribune.

"Going into fall, they'll give us bargain-basement deals," he said. "It's better (for the airlines) to get a few bucks than zero bucks."

Among the low prices from Chicago through October are less-than-$100 round-trip travel to Ft. Myers, Fla.; $503 round-trip flights to Honolulu, Hawaii; and 50 percent to 70 percent discounts on fares to Europe, compared with peak travel months June and July, Parsons said.