Lately, the transgender community’s push for more gender-neutral public restrooms has drawn a fair amount of attention, support, and criticism. I’ve been sympathetic to many sides of the debate. Of course transgender individuals should be able to use facilities for the gender which they live and identify as; and the creation of more unisex bathrooms seems, in general, like a good move. But providing unisex restrooms shouldn't be compulsory—there are both logistical and ideological reasons why businesses might oppose. Gender segregation is a long-established, common-sense norm in bathroom design... or is it? It turns out our views of traditional restroom delineation may be much like our views of traditional marriage: A myth.
Public restrooms have not always been gender segregated. "Historically, shared public latrines have been a feature of most communities, and this continues to be true in developing countries such as Ghana, China, and India," note Olga Gershenson and Barbara Penner in Ladies and Gents: Public Toilets and Gender.
"Private, sex-segregated lavoratories were a modern and Western European invention, bound up with urbanization, the rise of sanitary reform, the privatization of the bodily functions, and the gendered ideology of separate spheres."
According to sociology and sexuality studies professor Sheila Cavanagh, the first separate toilet facilities for men and women appeared at a ball in Paris in 1739. Until then, public restrooms, such as they existed, were generally gender neutral or marked for men only. The earliest efforts to legislate gender segregation in the United States were due to a lack of women’s facilities in workplaces.
In 1887, Massachusetts was the first state to pass a law mandating women's restrooms in workplaces with female employees. As far as I can tell, this was a pretty good idea; factories and other places that had begun to employ women were refusing to install restrooms for them. Perhaps the job market would have corrected itself eventually, but in the mean time working ladies had to pee.
By the 1920s, most states had passed similar laws. That all seems relatively fine, but the problem happened when the government went beyond merely mandating that employers give all employees a place to do their business to specifying exactly how and in what ratios this must occur, in and out of the workplace.
These days, America’s public restrooms are regulated by two separate federal agencies. Workplace restrooms are the purview of the U.S. Department of Labor, which sets state guidelines through the Occupational Safety and Health Administration (OSHA). Non-workplace public restroom guidelines are governed, broadly, by the Department of Health and Human Services.
More specific regulations are largely enacted though through state and municipal building codes. These codes dictate exactly how many toilets and/or urinals that buildings, businesses, and other public entities must provide, based on occupancy capacity. And they mandate not only the existence of separate men’s and women’s bathrooms but also how many "fixtures"(toilets or urinals) must exist for each.
"Restrooms are still almost exclusively gendered," writes Suzanne LaBarre Shaunacy Ferro at Fast Company. "It's a form of exclusion that's written into state building code, presenting an obstacle for gender neutral bathroom advocates."
In many places, businesses are legally prohibited from offering only gender-neutral restrooms. A small restaurant, coffee shop, or bar with only two (separate, enclosed) toilets must designate one for women and one for men. New York City only made it permissible in 2012 for restaurants and coffee shops with just two water closets to make these unisex, and only then for places with a total occupancy of 30 or fewer. (Washington, D.C., is one of the few places where it's actually illegal to designate single-occupancy restrooms as male- or female-use only.)
"Even in public spaces, such as restaurants, where two single occupancy, self enclosed toilet facilities are all that is provided to customers, signs designate one 'Stallions' and the other 'Fillies,' one 'Pointers' and the other 'Setters,' or, more prosaically, one 'Ladies' and the other 'Gents,'" writes University of Chicago law professor Mary Ann Case, in a 2010 article titled "Why Not Abolish the ‘Laws of Urinary Segregation’?"
Most state and local bathroom building codes are modeled on one of a few sets of international guidelines, such as the Uniform Plumbing Code or the International Building Code (IBC). On a broad level, these codes tend to require that all buildings have restrooms and that all occupants be allowed to use them.
Pursuant to these codes and state "potty parity" laws, public places are required not only to offer gender-segregated facilities but to offer a certain number of men’s and women’s "fixtures" depending on building/business size and type. For purposes of the fixture count rules, a building's total occupancy is considered to be half male and half female (i.e., a 100-person occupancy concert venue would be required to base bathrooms around an assumption of 50 men and 50 women).