US Patent 220,925, an improvement on her satchel-bottom bag machine, assigned to the Eastern Paper Bag Company.
On October 28, 1879, Margaret Knight patented a further improvement to her paper-bag manufacturing technology under US Patent 220,925. This refinement built upon her original 1871 design, enhancing the mechanism used to form the 'satchel-bottom' style bag — a durable, self-standing bag shape that became a staple of retail packaging.
The patent was assigned to the Eastern Paper Bag Company of Hartford, Connecticut, the firm Knight had helped establish in the early 1870s to commercialize her bag-making inventions. Assigning patents to a company in this way was a common business arrangement, allowing inventors to receive compensation (often royalties or a lump sum) while the company held manufacturing and licensing rights.
The patent model associated with this invention is preserved today in the collection of the Smithsonian National Museum of American History, a testament to its lasting historical and technical significance. This continued refinement of her original machine demonstrates that Knight remained professionally engaged with the paper-bag industry for nearly a decade after her initial breakthrough, continuously seeking to improve efficiency and reliability. Her sustained involvement in this field, at a time when few women held any patents at all, underscores her standing as a serious, ongoing contributor to industrial mechanization rather than a one-time inventor.