One interesting finding was the large number of envelope companies which thrived in Worcester through the early and mid-1900s.
While Worcester had a number of large printing companies over the last two hundred years, in some cases no company records were found at area repositories. Perhaps materials are held by private individuals. It also seems that many companies disposed of brochures and other company materials once they were no longer current.
The American Antiquarian Society has an extensive collection of materials of Isaiah Thomas. The AAS also has records of other early Worcester printers, and its "Worcester Collection" contains records of some Twentieth Century Worcester printers.
Other repositories hold large collections of records of a few printing companies. Yale University has the Merriam Archives. Worcester Polytechnic Institute's Archives and Special Collections holds the Woodbury Company Archives, including many large Bird's Eye View drawings. The Clinton Historical Society has a substantial collection of Colonial Press's records. And the Worcester Historical Museum has several boxes of George C. Whitney Co. materials, including many samples of Valentines and other cards.