Why aren't there more unisex bathrooms? Blame building codes for long lines, unhappy transgender people, grumpy business owners, and more.

• Author: Brown, Elizabeth Nolan

Lately the transgender community's push for more gender-neutral public restrooms has drawn a fair amount of attention, support, and criticism. The proliferation of unisex bathrooms seems like a logical solution to the tricky problem of figuring out who gets to pee where. Providing restrooms where all are welcome shouldn't be compulsory; there are both logistical and ideological reasons why such a mandate is a bad idea. But what's holding us back from opening up more restroom doors?

Despite what you might think, 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 their 2009 book of essays Ladies and Gents: Public Toilets and Gender (Temple University Press). "Private, sex-segregated lavatories 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. By the 1920s, most states had passed similar laws.

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 through state and municipal building codes. These codes dictate exactly how many toilets and/or urinals buildings, businesses, and other public entities must provide--in separate men's and women's facilities.

"Restrooms are still almost exclusively gendered," wrote Shaunacy Ferro at Fast Company in April. "It's a form of exclusion that's written into state building code, presenting an...