09/30/2026
You probably have one sitting somewhere in your house.
A plain brown paper grocery bag.
But the familiar flat-bottomed bag has a patent history stretching back more than 150 years.
Margaret E. Knight worked around paper-bag manufacturing and saw a problem she believed machinery could solve. She developed a machine capable of cutting and folding paper to produce flat-bottomed bags.
In 1871, Knight received U.S. Patent No. 116,842 for an improvement in paper-bag machines.
And she kept inventing.
In 1879, she received U.S. Patent No. 220,925 for another improvement involving the mechanisms used to fold and paste the bottoms of the bags.
Her work mattered.
The Smithsonian, which preserves a patent model of Knight’s later machine, notes that her concept continues to be used in manufacturing the paper grocery bags we know today.
I love patent stories like this because the finished invention doesn’t look extraordinary anymore.
That is precisely the point.
Successful inventions can become so integrated into everyday life that eventually we stop seeing the invention at all.
We just see a paper bag.
Margaret E. Knight | Paper-Bag Machines | 1871 & 1879