In the past, mining towns in northeast Minnesota were the battlegrounds in hard-fought labor disputes. One weapon used by the steel companies was a vast, intricate spy system among their workers. Chisholm native Tom Selinski has created a video documentary, "Spies in Steel," describing that era, and how the spy network was ultimately exposed. Minnesota Public Radio's Amy Radil reports. Today union offices occupy some of the most prominent buildings in Iron Range towns. But in the early part of the century, union meeting places were makeshift -- and clandestine. Workers met in storefronts and basements, knowing they'd be fired by the mining company if their union membership was revealed. Raising the stakes, and increasing the risks were company spies...in barber shops, hotels, and among their own members. Tom Selinski grew