Unisex v. Single Sex v. Multisex

Megan McArdle wants to know "Why don't we have single sex bathrooms?" Of course, we do, since all public toilets are single sex. But I suspect Megan is really referring to unisex bathrooms, known in the architecture business by the high-brow term "one-holers." Answer: We're working on it.

The new International Building Code has this provision:

The International Building Code establishes where and when unisex toilet facilities are required. The 2000 and 2003 editions of the IBC require unisex toilet facilities in assembly and mercantile occupancies that are required by the plumbing code to have an aggregate of six or more water closets in male and female toilet rooms.

Of course, it is possible that Megan is wondering why we don't have multi-sex toilet rooms, as opposed to unisex or single sex. The answer to that question is, I believe, we used to. New York aficionados will remember that when, McSorley's was compelled to admit women in 1970, there was but one rest room, and it was fully shared. As I recall (it's a foggy memory I admit), we got on fine.