As part of its effort to control costs, Southwest historically used secondary airports in cities where the primary airports have high costs, such as Chicago, Dallas/Fort Worth, Houston and Miami. In recent years however, the airline has been expanding into primary airports as well. In most cities where Southwest uses both a primary and secondary airport, the secondary airport is used more than the primary for flights (such as Oakland instead of San Francisco), with some exceptions such as the Los Angeles metro area, where Los Angeles International is a Southwest base and secondary airports (such as Burbank, Long Beach, Santa Ana and Ontario) have limited Southwest operations despite having a higher market share at the smaller airports.
