Passenger traffic at Des Moines International Airport continued to grow in February, with passenger counts up 3.8 percent over the previous February. That leaves year-to-date traffic up 3.4 percent. The biggest year-over-year growth in February, on a percentage basis, came at Southwest Airlines at 25.7 percent, followed by Delta Airlines at 12.6 percent. United Airlines was the sole loser among the large airlines, falling 16 percent. The carrier with the most passengers, American Airlines, saw a 9 percent jump in passengers in February.