A man stole her invention and told the judge no woman could design something so complex. She walked into court with evidence that destroyed him.
A courtroom in Massachusetts.
Charles Annan stood confidently before the judge, presenting his defense with smug certainty. A woman, he argued, could not possibly understand the complex mechanics of the machine in question.
He had seen the prototype at a Boston machine shop where the designs were being built. He assumed the real inventor—a factory worker—wouldn't fight back.
He was catastrophically wrong.
Margaret Knight wasn't just a factory worker in Springfield, Massachusetts. She was a mechanical genius who had been inventing since she was twelve years old.
The problem she solved had plagued the paper bag industry for years. At the time, paper bags were useless—more like envelopes, flimsy and narrow, impossible for carrying groceries. Workers had to fold and glue square bottoms by hand, which was slow, expensive, and inefficient.
Margaret envisioned a machine that could cut, fold, and paste bags automatically, creating the flat-bottomed bag we still use today.
She spent two years refining her design. She built a wooden model that worked perfectly, but she needed an iron prototype to secure the patent.
She sent her designs to a machine shop in Boston.
That's where Charles Annan worked.
He saw the brilliance of the device immediately. He copied it, filed a patent for the exact same machine, and claimed it as his own invention.
When Margaret went to file her paperwork, she was rejected. Someone had already patented her design.
Instead of accepting defeat, she poured her life savings into a lawsuit.
Annan's entire defense rested on the prejudice of the era. His argument was simple and insulting: no woman could design such sophisticated machinery. The complexity alone proved a man must have invented it.
Margaret realized she didn't need him to believe in her. She just needed the judge to see the truth.
She arrived at the patent interference case with overwhelming evidence.
Original sketches from years prior, documenting the idea's inception. Detailed diaries recording every modification and adjustment. Witness testimony from the mechanic who built the prototype under her direct supervision, confirming she designed every component.
The documentation was irrefutable.
The court had no choice but to accept reality.
The Commissioner of Patents ruled that Annan had stolen the design, stating: "Miss Knight has established... priority of invention."
She won her patent in 1871.
She went on to co-found the Eastern Paper Bag Company, bringing her invention to market and revolutionizing an entire industry.
But Margaret didn't stop there.
Over her lifetime, she accumulated 87 patents—inventing everything from window frames and shoe-cutting machines to improvements for rotary engines and automotive components.
Her contemporaries called her "Lady Edison."
Yet today, most people have never heard her name.
Margaret Knight died in 1914 at age 76. Despite her innovations generating millions in value for American industry, she died with modest means. The system that tried to steal her invention never fully compensated her genius.
But her legacy lives on in every paper bag we use.
Every time you pack groceries, carry lunch, or hold a gift bag, you're using Margaret Knight's invention—the flat-bottomed paper bag that she designed in the 1860s and defended in court against a man who thought her gender disqualified her brilliance.
Her story is a reminder of three truths:
Skill has no gender. Documentation beats arrogance. And justice, though delayed, sometimes prevails when someone refuses to back down.
Margaret Knight didn't just invent the modern paper bag. She proved that when women are underestimated, preparation and perseverance can demolish prejudice.
She walked into that courtroom with bags full of evidence—and walked out with victory.