I went to college in Lowell, Massachusetts. That is where General Benjamin Butler set up the United States Bunting Company. That company press-dyed stars and stripes onto wool bunting using an 1870 patent. I have 13-star and 38-star flags with either the April 1870 patent info or the stamp "United States Bunting Company" on the heading. I have seen 37-star flags made with this process also and can only assume they also carry the 1870 patent date.
The United States Buntinc Company was the first company in the USA to manufacture wool bunting (it had all been imported from England in the past.) And, as a congressman from Massachusetts, he got Congress to pass a law giving preference in Government purchasing to flags made of Domestic bunting. Now, would we call that a conflict-of-interest today or what?!?
See the link below for a 38 star Ben Butler flag that just sold on eBay for $126
My college begain in 1895 as the Lowell Textile School. It is now part of the UMass System.