Here's a bit of labor market gloom-and-doom:

The uncomfortable reality, as Andrew Sum sees it, is that there's a direct link between the steep national decline in teen employment rates and the growing practice of businesses hiring illegal immigrants and paying them off the books.

Teens also face increased competition from 20- to 25-year-old college graduates who have been driven into less attractive jobs unrelated to their fields or who are vamping for time as retail clerks, waitresses and on-the-books construction workers.

My hunch--rising income has much more to do with declining teenage employment than illegals working off the books and all of the other pessimistic possibilities. I'd also suggest additional possibilities not included in the article--increasing college enrollment rates and structural changes over time (a smaller share of output in seasonal industries).

Prof. Sum seems to be a perpetual pessimist--here are his takes on 2003 and 2004. Interestingly, the 2003 blurb indicates that the National League of Cities commissioned the 2003 study. Interestingly, Prof. Sum's solutions include more spending on teen job programs. Coincidence?

ADDENDUM: Prof. Sum's hypothesis that illegals (and other factors) are crowding out domestic teens is testable by regressing state employment/pop rates on factors including estimates of the illegal population in each state. If I can endure BLS's awful website, I might revisit the topic.