American Airlines has announced a major restructuring of its route system, with hubs in Dallas/Fort Worth, Chicago and Miami all expected to see double-digit flight growth. Chicago O'Hare will be the major beneficiary, with 57 additional flights each day, largely offsetting American's 13% cutback in operations over the past year. New York, Los Angeles and San Juan, Puerto Rico, also will see a boost in flights, while St. Louis will lose 65 daily flights and workers will be reassigned to other cities. "St. Louis and Chicago are two mid-continent hubs," said a company official. "In the current environment you simply can't sustain that."