Who labels Hardwood Floors?

As I was ripping up some old floors in an old 70-80 year old apartment building, I noticed the MADE IN USA label along the bottom of each and every board I pulled up.  It just made me think of when we buy shoes or any leather made goods, we often look to see where it's made, thinking (or knowing) that it's better because it's from a particular country of origin.  I just thought it was odd that the floors also were labeled, albeit face down for no one to see......until now......