Margaret E. Knight

Margaret E. Knight was only 12 years old, but, like many children in 1850, she was already working in a cotton mill in Manchester, New Hampshire, spending her days in hot, dusty, crowded rooms filled with the constant clatter of the looms. These machines ran fast, and when something failed, it often did so violently and sometimes tragically.

One day, as a loom wove cloth, a steel-tipped shuttle suddenly shot from the frame and struck a worker. Margaret saw the blood and pain and watched the panic that followed.

Most children would have walked away from the experience with a memory of fear. Perhaps Margaret did as well. But she took something else away from the incident. She wanted to solve the problem.

Margaret had always liked building things. Her sleds were admired by people in the neighborhood, and she often devised small tools and household improvements. So after the accident, she began working out a way to keep the shuttle from leaving the loom. Soon she devised a guard that prevented the shuttle from flying loose even if the threads snapped or the mechanism slipped. The change was simple enough to be fitted to existing looms.

The mill adopted her solution. Others followed, and injuries were reduced. She never patented the invention. But she had discovered that her love of building could solve others’ problems.

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Margaret would build many mechanical devices throughout her long life. But the one that has impacted the world most and longest began around 1868, when she was working at a paper bag factory in Springfield, Massachusetts. The bags being manufactured there were simple, folded pouches, glued along the sides with no flat bottom. When opened, they formed a loose sack that would not stand upright on a counter. They were the standard in use at the time and were problematic.

Shopping then differed from what later generations would know. Customers did not browse aisles or select goods from shelves. Instead, they stood at the counter and placed their orders with the shopkeeper, behind whom were barrels and bins filled with flour, sugar, rice, coffee beans, and sometimes small hardware items, among other products. Nearly everything was sold loose, measured to order, and each product purchased would be placed in its own bag.

The existing bags made this difficult. Because they would not stand on their own, the clerk had to hold the mouth open with one hand while pouring with the other, all while watching the scale to see when the pointer reached balance. The paper shifted, folded inward, or tipped. If the bag collapsed, the contents spilled, and the weighing had to begin again. Clerks sometimes developed their own small tricks, including propping bags against jars or wedging them between their bodies and the scale. But these were workarounds, not solutions.

Flat-bottomed bags that could stand upright and hold goods securely did exist. But they had to be folded by hand, which took time and skill, and no two looked quite the same. And there was no machine that could produce one reliably — the mechanics were too complex.

Margaret believed a machine could do the needed work, and set out to create one. She began designing a mechanism that would cut, fold, and glue paper into a bag with a square bottom. In her boardinghouse, she constructed a wooden working model, adjusting gears and movements until the sequence operated correctly. When it performed reliably, she arranged for an iron version to be built at a machine shop.

While the iron model was being built at the shop, a machinist named Charles Annan saw the design and applied for a patent on a similar machine.

Margaret contested the claim, and the dispute became a patent interference case in the early 1870s. Annan asserted that the invention was his and pointed to the era’s assumptions about women and mechanical skill, arguing that such a machine could not have been designed by her.

Margaret answered with evidence. She brought her sketches, notes, and wooden model to the hearing, and witnesses testified they had seen her developing the machine. She explained the mechanism in detail, describing how each component functioned and why it was necessary.

The court ruled in her favor. Margaret received U.S. Patent No. 116,842 for the flat-bottomed paper bag machine. Then, she helped establish the Eastern Paper Bag Company, and the design went into mass production. The form she created became the standard paper bag used across the United States and eventually in much of the world.

But Margaret didn’t stop there. Over her lifetime, she received at least twenty-six patents, though some records suggest there were more. She designed machines for cutting shoe soles, improvements to rotary engines, window frames and sashes, dress shields, and numbering mechanisms, among other inventions.

Margaret never married and lived modestly, investing much of her earnings back into experimentation and new designs. When she passed away in 1914, her estate amounted to only a few hundred dollars (about $9k today), and her name soon slipped from public memory. But her work continued to be used worldwide.

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Sources:

• Abrams, Michael. “Margaret Knight.” The American Society of Mechanical Engineers, https://www.asme.org/topics-resources/content/margaret-knight

• Boston Sunday Post, 1912 - Newspaperarchive.com / Wikimedia Commons, Wikimedia Foundation, https://commons.wikimedia.org/wiki/File:Margaret_knight_boston_sunday_post_march_31_1912_p.45.jpg

• "Margaret E. Knight.” National Inventors Hall of Fame, https://www.invent.org/inductees/margaret-e-knight

• PETROSKI, HENRY. “The Evolution of the Grocery Bag.” The American Scholar, vol. 72, no. 4, 2003, pp. 99–111. JSTOR, http://www.jstor.org/stable/41221195. Accessed 20 Feb. 2026.

• Smith, Ryan P. “Meet the Female Inventor Behind Mass-Market Paper Bags.” Smithsonian Magazine, https://www.smithsonianmag.com/smithsonian-institution/meet-female-inventor-behind-mass-market-paper-bags-180968469/