I was a little worried about my checked bag that I had to leave at Pittsburgh airport last night after changing my flights to Seattle at the last minute, but I discovered that Delta’s smartphone app lets one scan the bag tag (the sticker you get when you check the bag) to determine its location : pretty neat. So the bag was pulled last night from my original Pittsburgh-Minneapolis flight and put on the one this morning. The airport at Minneapolis was crowded, with lots of families traveling. The US airlines expect the most fliers in five years for 2013 – but not quite reaching the all-time high volume of some 217 million travelers that flew in 2007, the industry’s high point.