Wikipedia is talking about USG before the reorganization in 1923 & there were actually two factory Gs, one Gillinder which was sold in 1907 & Glassport which opened in 1894. 1/2 of the old conglomerate was gone by that time, Challinor Taylor, Richards & Hartley, Bellaire Goblet, O'Hara, Columbia, etc, etc, etc. I'll try & simplify this. In 1923 USG reorganized because many of the original ancilliary companies had either gone out of business or had dropped out of the conglomerate. What replaced them were simply factories not individual companies operating under the USG reorganization. Many of these factories continued as part of USG until the 2nd reorganization in 1937 when USG headquarters moved from the Pittsburgh area to Tiffin, Ohio (Factory R) & this remained relatively intact until 1962 when USG went bankrupt. Now what causes confusion is that prior to September 1927 many USG products produced after the 1923 were labeled either with an inpressed USG in the glass or a USG paper label. In September 1927 all glass produced within USG regardless of what factory produced it was labeled Tiffin by paper label. Confusing? yes, but its typical of what happened within many conglomerates during this time in the US. Now Tiffin Factory R continued on after the USG 1962 bankruptcy as the Tiffin Art Glass Company when former employees purchased it from the bankruptcy proceedings & it remained open under several different ownership changes until 1980 when it finally closed. Glassport Factory G was still in operation until it was destroyed by a tornado in 1963 that by todays standards was at least an F3. Ken