AC/DC fans have helped sell out many venues in record times and numbers for the band's upcoming World Tour.  Due to the response, Chicago, L.A. and Oakland are forced to add second dates.
 

• Chicago's Allstate Arena concert sold out in minutes forcing the second show to go on sale, which also sold out over the weekend.
• Both Madison Square Garden concerts sold out in minutes.
• Vancouver's General Motors Place concert sold out in 4 minutes, a record for that venue.
• San Antonio fans purchased more tickets in one day for AC/DC than for any other artist in that market's history.
• Tickets for Toronto's Rogers Centre sold faster than any stadium concert in the venue's history.

As of 1:00pm today, tickets were still available for the Philadelphia show. Philly, typically a rock town, I thought would highly support this show. But the sell outs have been harder and harder to come by in Philadelphia. It took Metallica almost two weeks to sell out the Wachovia Center when they were selling out other locations in minutes.
 
Without getting into an economical discussion, I believe due to the hard working atmosphere of the usual Philadelphian and the way the economy is taking a down turn, has lead to this problem. People just have less time and money to spend on "non essential" things like concerts, baby formula, and condoms.

So I believe that concerts will be attended ok, but not sell out capacity for a couple of months in Philadelphia. But, because people are forced to stay home from these concerts, the birth of babies in the next 9-12 months will skyrocket.
 
But I was an English major in college and a pretty poor one at that, so what do I know?