Actually, according to the WN website today, Midway is currently #2 with 208 daily departures. McCarran/LAS is #1 with 212. The September 2010Southwest/AirTran fact sheet showed WN with 224 daily departures at LAS, and 216 at MDW.

Flights from McCarran have been reduced (I believe they had 233 daily flights a year ago) as WN has redeployed aircraft elsewhere and ramped up new service without adding aircraft in 2010. Presumably the number of daily flights from LAS will increase once they start adding aircraft — or not.

Clearly, ATL clearly will be in WN's top 5 for daily departures once the acquisition of AirTran is approved. The fact sheet I referred to above showed AirTran with 202 daily departures from ATL as of September 2010.