Second, the development of Formica, fiberglass, and other plastics made it cheaper to build bathrooms with that particular mid-century shine. From 1910 to 1940, the average sale price of a bathtub declined by 70 percent, according to the historian Alison K. Hoagland, the author of The Bathroom.
Third, suburban developers started offering, and middle-class consumers started expecting, an en suite bathroom in the master bedroom, which created a need for another bathroom that was accessible to kids and guests.
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American bathrooms haven’t grown only in number. As the square footage per person in a new single-family home doubled from the 1970s to the 2010s, so too did the typical size of a bathroom—from 35 square feet to 70, according to Hoagland. They’ve also grown in importance, taking on new, ever more fanciful roles, serving as “powder room, laundry room, phone booth, library, gymnasium, storage closet, and, for the affluent at least, a place of sybaritic luxury,” as Newsweek wrote in 1965.
Larger and more voluminous bathrooms, with their deeper shower shelves and taller medicine cabinets, gave individuals more room for beauty equipment, lotions, serums, shampoos, conditioners, soaps, creams, and makeup brands. Since Diane von Furstenberg published The Bath, her influential ode to the commode, in 1993, affluent Americans have transformed their bathrooms into technological marvels, with Jacuzzis, steam showers, rainfall heads, and other gizmos to reproduce various tropical microclimates.
This is the bathroom’s impressive 100-year evolution in the United States: What was once a foul cesspool has become a human car wash.
You might think that we have already reached Peak Bathroom. But the super-rich have other ideas. Last year, The Wall Street Journal reported on a Bel Air, California, home that listed for $49.9 million. It featured eight bedrooms—and 20 bathrooms. By any rational assessment, this is a ludicrous use of money, space, and plumbing. But the U.S. housing market is rarely restrained by rationality. Indeed, the share of houses with 10 or more bathrooms has doubled in the past decade. It would seem that the richest 0.01 percent of Americans are spending down their fortunes in an arms race for toilets.
Even among non-zillionaires, the numbers show that bathrooms are still the prize of the 21st-century American home. According to Zillow research shared with The Atlantic, a simple bathroom remodel—such as replacing the toilet, adding a double sink, or tiling the floor—carries the best bang-for-buck of any home renovation. At $1.71 in additional home value for every $1 spent, it’s three times as cost-effective as a kitchen renovation. (The simple reason: Different couples value different kitchen utilities, but there are only so many ways to use the can.)