Jacob received U.S. Patent No. 1,115,674 for the 'Backless Brassiere,' the first U.S. patent for a modern bra design.
On November 3, 1914, the United States Patent Office granted Mary Phelps Jacob U.S. Patent No. 1,115,674 for her 'Backless Brassiere' design. This moment is the best-documented and most significant 'first' in her biography: she became the first person to receive a U.S. patent for a modern brassiere design.
While earlier bust-supporting garments existed in various forms across history, Jacob's patent was distinct in codifying a lightweight, flexible design intended to replace the rigid corset — marking a turning point in the engineering and marketing of women's undergarments in America.
The grant provided legal protection for an invention born of personal necessity, and it foreshadowed a seismic shift in the fashion industry. Jacob briefly ran her own company, the Fashion Form Brassiere Company, before selling the patent rights to the Warner Brothers Corset Company, which went on to earn enormous profits from the design over subsequent decades.
This achievement cemented Crosby's place in the history of invention and women's fashion, and it is frequently cited as a landmark moment of female ingenuity in a male-dominated patent system.