Bag-check fee catches on — and $2 a pop for pop!!

No. 2 airline United and No. 7 U.S. Airways have joined No. 1 airline American in charging $15 for fliers’ first checked bag.

I’m betting, still, that Southwest doesn’t join the stampede, and winds up using this to actually increase its profit margin.

And, no more free sodas on U.S. Airways — it’s $2 a pop for pop now.