One of my vendors is at the U.S. Open helping with preparations, he sent me a picture of the crew they have (Oakmont crew + volunteers).
It truly takes an army of men and women to pull off an event like this. To produce that type of product, it takes over 100 people to get it all done.
I've shared this picture before, this was at the 2005 PGA Championship that I helped with, we had an army then as well.