Three times a day come June. Interesting addition, as again the airline avoids expanding to the biggest obvious voids in its North American operations: Secondary markets between Oklahoma and Indiana.

Update: Found figures for U.S.-Canada air service. Philadelphia – Quebec City traffic amounted to some 2,250 passengers in 2009. That’s not 2,250 round trips but rather “total outbound plus inbound passengers.” That comes to about 6.2 pax/day. 2010 was a better year than 2009 for air travel and there’s also probably some seasonality involved. (The Canadian methodology is similar to that used by the DOT in the data linked to above except the DOT reports by quarter not year.) Still, it’s a fascinating choice given the much larger unserved domestic markets available from both CLT and PHL.