Why Twin XL Beds Dominate College Dorms

The slightly longer mattress is a compromise between schools’ economic needs and students’ physical ones.
Alia Wong –
In the late 19th and early 20th centuries, several outbreaks of infectious disease in the U.S., including the flu, tuberculosis, and pneumonia, prompted public-health officials and homemaking experts to suggest a tweak to American bedrooms as a safety measure: Couples (and children) sleep in separate beds. As a result, twin beds quickly entrenched themselves as a staple in American homes and remained popular long after the plague outbreak was over. In the mid-20th century it was still relatively rare to see depictions of married couples sleeping in the same bed (see: I Love Lucy, The Dick Van Dyke Show).
Eventually, twin beds’ popularity among American adults more or less faded into obsolescence, Hinds writes; today, queens are the most popular mattress size purchased, according to Consumer Reports. Kid-size beds have since been mostly consigned to kids—minus one notable exception: college dorms. Of course, the college-dorm mattress is no standard twin, but what’s known as the twin extra-long (XL), five inches longer than its traditional counterpart. The twin XL has a twin-size width—helpful given dorm rooms’ limited space—and its king-size length, presumably, is a bone thrown to the comfort of students whose bodies are, after all, adult-size.
continue: Why Twin XL Beds Dominate College Dorms – The Atlantic