Southwest Airlines, the nation’s largest domestic carrier in terms of passengers carried, has proudly served St. Louis for 25 years. Southwest currently operates 72 daily nonstop flights from Lambert-St. Louis with additional or connecting service to 42 destinations. The airline will add non-stop service to 6 new destinations in the Spring, making it the dominant airline serving St. Louis in terms of daily departures. Remember, on Southwest Airlines your Bags Fly Free! (weight and size limits apply).