You are correct, and I was mistaken. It appears that more than 50% of the states (at least 28, as you correctly counted) do indeed have a polygraph licensing requirement.

Thank you for the information.  I looked at the APA website.  They list 28 states which require polygraph examiner licensure of some type.  That is 56% of the states in the Union.  With polygaph so widely used one would think examiners should be licensed or at minimum accountable to some type of oversight.  Without licensure these folks are free to interpret and conduct exams in any way they please.  Ridiculous.

It seems that most states have no licensing requirement for polygraph operators. Considering that polygraphic lie detection lacks any scientific basis, I think it's appropriate that there should be no licensing requirement to practice it, just as one shouldn't need state certification to offer tarot card readings.

You'll find a list of states that do have licensing requirements for polygraphers, along with contact information for their licensing boards, on the American Polygraph Association website. (I don't know whether this list is comprehensive):

http://www.polygraph.org/statelicensing.htm

I have recently been made aware that Arizona has absolutely no oversight for poly examiners.  No certification, licensure, required schooling, etc.  Absolutely no regulation whatsoever.  Is this the case in any other states?