President Bush told Americans today they could help revive the economy and strike a blow against terrorism by taking to the air. Speaking to airline workers at Chicago's O'Hare Airport, the president promised federal oversight of passenger and baggage screening. He said billions of dollars would go for stronger cockpit doors and armed U.S. air marshals on board commercial flights. And he called on all 50 governors to use National Guard troops in airport security until the new measures are all in effect. NPR's Don Gonyea reports from Chicago.