Top Law Schools

I'm writing a cover letter for a career fair, and a lot of the firms, government agencies, and PI organizations do not list the names of their representatives at the fair. How should I address the cover letter? Dear sir or ma'am?

I think that's probably a pretty non-offensive way to go. The only other option I'd suggest is "To Whom it May Concern" but overall I find that to be a bit cold and overly formal.

Or maybe "Dear Head of Recruiting" or whatever their title would be.

My career center lady said to call the organization and find out who is in charge of hiring.

Annoying, but it sounds like the right idea.