In Minnesota, summer is the season of roof work. But a glance at the crews overhead this time of year makes it clear most people doing that work are not from Minnesota. The residential roofing industry around the country now relies on low-priced labor by Mexican immigrants. Industry insiders say the roofing business would collapse without this migrant work force -- which includes immigrants who are in the U.S. legally and illegally. But as Minnesota Public Radio's Jeff Horwich reports, few people are happy with current state of things.