Pyramids in the United States

I have come to learn, mostly from speakers on Portal to Ascension webinars, that the United States has many pyramids.  

In other words, a vast quantity.  

I get the impression this information is not mainstream. 

I also get the impression that when most people think of pyramids, they think of Egypt.  But there are other pyramids in other countries.  What does the Galactic Federation think?