From
www.snopes.com (sorry this is long, but I can't make a direct link):
Origins: This mistaken belief has been recorded since the 1960s and is probably a great deal older than that. It's possible its origin lies in a mental confluence of half-remembered tidbits about old time "blue laws" mixed with a healthy dollop of badly-parsed newer input about zoning laws adopted by various communities in more contemporary times. Short and sweet, if any so-called "brothel laws" anywhere tie a building's classification as a bordello to the number of occupants, we've yet to find documentation that proves this.
Some municipalities do indeed have zoning laws prohibiting more than a specified number of non-family members (male or female) from living together, but not even in those cases would a household in violation of those codes be labeled a brothel. Brothels earn such designations solely on the basis of what goes on in them, not upon how many women inhabit particular buildings.
Even in communities that carry such housing restrictions on their books, sororities and fraternities are exempted from them. The thrust of such laws is to set limits on how many people may reasonably inhabit what were meant to be single-family dwellings, not to enjoin those who are living in more communal settings in buildings meant for such purposes. Were such laws to apply to those latter forms of housing, local YWCAs would have been shut down and padlocked, as would a variety of nurses' residences.
Collegians have been explaining the lack of sorority houses on various campuses through this flawed factlet for many a year. Richard Roeper noted this legend in 1994, calling it "the most widespread piece of university folklore making the rounds" and estimating from entries on collegiate bulletin boards that it was being told on at least 100 campuses.
Men view the notion of large numbers of women living together as strangely erotic, mentally envisioning a veritable candy store of comely and available sex partners, each of them bedding down for the night virginally clutching her teddy bear close to her babydoll-clad, pulsating 38-24-36 nakedness (which they wouldn't if they'd ever been locked in a women's dorm overnight -- nothing kills rampant sexual fantasy more quickly than a cold eyeful of reality.) Add to the mix the "college girl" element (young, nubile flesh) and throw in the "sorority girl" detail (presumed promiscuity), and it's easy to see why this tidbit about brothel zoning has been so stubbornly promulgated.
Barbara "daydream believers" Mikkelson
Last updated: 6 August 2002
If AZ is different, I'd like to see the state code that supports it. I am willing to bet there are women's shelters in the state, for example, or a hotel (which unless it's tiny has more than 6 women there) - or for that matter I bet there are dormitories in AZ with more than six women in them.