Heraldry is unregulated, and, aside from the Seal of the United States, unprotected in any way. There are some private, unofficial organizations which have established rolls of arms or registers. One such is the New England Historic Genealogical Society, whose Committee on Heraldry has been publishing an armorial of American families (see also the bibliography).
There are other organizations, one of which is the American College of Heraldry: this is a non-official, non-profit organization devoted to heraldry.