National Underwear Day

The global underwear market was valued at approximately $90 billion in 2023 and is projected to reach $140 billion by 2032. That figure covers a garment most people think about only when choosing one in the morning or replacing one that has worn out. Underwear is the most universal piece of clothing on the planet, worn across every culture and climate, yet it receives far less attention than any outer garment.

National Underwear Day exists to address that gap. The observance started as a promotional event by an online retailer but has grown into a broader celebration of body confidence and the surprisingly deep history of the garment closest to skin. Underwear has been shaped by technology, social norms, gender politics, and material science for over 7,000 years, and its evolution mirrors larger shifts in how societies think about the human body.

National Underwear Day celebrates one of the few garments that virtually every person wears but rarely thinks about historically. The evolution from animal-hide loincloths to a $90 billion global industry tracks closely with broader shifts in technology, manufacturing, gender norms, and body culture.

The loincloth is the oldest known garment of any kind. Archaeological evidence places its use at over 7,000 years ago, made from animal hides, bark, or woven plant fibers. By 3000 BCE, the Egyptians had formalized the concept with the schenti, a linen loincloth whose length and quality indicated the wearer's social rank. Roman athletes and laborers wore the subligaculum, a wrapped undergarment secured at the waist.

Medieval underwear and the question of women's underpants

In medieval Europe, men wore braies — loose linen trousers that extended to the knee or ankle and were tied at the waist. As outer clothing evolved, braies shortened and became recognizable undergarments. Women wore the chemise or shift, a loose linen garment worn directly against the skin. The chemise served a practical function: it was washed frequently while outer garments, which were expensive and difficult to clean, were not.

One of the most surprising facts in clothing history is that European women generally did not wear separate underpants until the 19th century. The chemise alone served as their undergarment. Drawers for women emerged in the early 1800s and remained controversial for decades, as they were associated with men's clothing.

Industrialization transforms undergarments

The spinning jenny (1764), power loom (1785), and sewing machine (1851) made mass production of textiles practical for the first time. Underwear, previously sewn at home or by tailors, became a manufactured product. The union suit — a one-piece undergarment covering the torso and legs — dominated the late 19th and early 20th centuries.

The modern bra emerged in 1914 when Mary Phelps Jacob patented a design made from handkerchiefs and ribbon, offering an alternative to the corset. Coopers Inc. (now Jockey) introduced the first Y-front briefs in 1935, giving men a supportive alternative to boxers. Boxer shorts, modeled after the garments worn by prizefighters, had appeared in the 1920s.

Synthetic fibers and the modern era

DuPont's introduction of nylon (1938) and Lycra spandex (1959) transformed underwear from a utilitarian necessity into a product defined by comfort, fit, and fashion. Rudi Gernreich popularized the thong in 1974. Boxer briefs, combining the coverage of boxers with the fit of briefs, arrived in the 1990s. Today, the global underwear market is valued at approximately $90 billion, with the sustainable underwear segment alone reaching $1.8 billion as consumers demand organic cotton, bamboo, and recycled fabrics. National Underwear Day, launched in 2003, arrived just as the industry was transforming underwear from a private necessity into a public statement of identity and self-expression.