>>>”major IT security industry organizations in the USA are?” is a matter of perspective. If you are looking for a purely American security institution that can provide “one stop shop”. I would have to say… National Security Association. This is not a place where you would, let us say, walk in the front door. If you are looking for ametures, trinkets, or “buttons”, Gartner is one of the larger “fox hunting groups”. I wouldn’t say they are intrinsicly U.S. They will file their corporation where ever would save them vs play their products. [Standard Public Market play]. Don’t expect them to have any quantum-computing binaries, or super-positioned/ entangled neural nets. About the best you can “contact” [the best contact you] is “diapers and beer”. My experience has shown that most people find “Planet Lab” hard to digest into their reality.
I read this as a request for professional associations. Many professional organizations are international but have local chapters. ISSA and ISACA come to mind. Beyond that, there are the bodies that handle IS certifications like (ISC)2.