The improvement in the economy definitely has something to do with it. I was involved in a project on recruitment back in 2000, and so read the scholarly literature on it. All the statistical studies show strong negative correlations between enlistment rates and job opportunities for 18 year olds.

However, that's not the whole story today; economic conditions haven't improved nearly enough to fully explain this year's shortfalls. That's especially true given that there are larger bonuses available now than in 1999, more recruiters out there, and greater access to schools than was the case in 1999 (part of No Child Left Behind).

To find another source of the shortage, you don't have to look any farther than poll results showing a dramatic decline in the percentage of parents who say they'd encourage their child to sign up -- down from nearly 50% two years ago (or in 1999 for that matter) to more like 25% now, according to one recent survey. Those same studies I mentioned also showed that parental encouragement/opposition was a very significant variable. The fact that the problem is so concentrated in Army recruitment vs the USAF or Navy is further evidence (in the 1999 crunch, the Army was also hardest hit but problems were much more even between the services than today).