Margaret E. Knight: The Flat-Bottom Paper Bag Inventor Who Beat a Thief

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Margaret E. Knight was born in York, Maine, in 1838 and asked for a pocketknife and gimlet instead of toys, building sleds and kites for neighborhood children. After her father's death the family moved to Manchester, New Hampshire, and by 12 she was working in a cotton mill. When a steel-tipped shuttle flew out of a loom and stabbed a worker, she designed a stop mechanism that other mills adopted, though she never patented it. Poor health pushed her out of the mills into home repair, daguerreotype photography, engraving and upholstery. In 1867 she joined the Columbia Paper Bag Company in Springfield, Massachusetts, and set out to automate the folding of flat-bottomed bags, which had been glued by hand while machine-made bags followed Francis Wolle's narrow V-bottom design.

While a machine shop built her iron patent model, machinist Charles Annan copied the design and filed a patent first. In the 1870 interference case he argued a woman could not understand such machinery, but Knight produced hand-drawn plans, journals and witnesses dating to 1867 while paying about $100 a day in legal fees, and won her patent in 1871. Queen Victoria decorated her, and she founded the Eastern Paper Bag Company in Hartford, taking capped royalties. She went on to shoe-sole cutting machines, household items and, in her seventies, rotary and combustion engine parts, with roughly 27 to 30 patents. She died in Framingham in 1914 with an estate of a little over $275.

• She signed her 1870 patent for a paper feeder with her full name rather than initials.
• Suffragists called her a woman Edison and used her engine patents against a physician who claimed women were uninventive.
• A 1913 New York Times profile reported her working 20-hour days at 75 on her 89th project.
• Luther Crowell later added the accordion side fold in 1872, but the flat bottom design is hers.
• She entered the National Inventors Hall of Fame in 2006, and MoMA showed the bag in a 2025 exhibition.