There were and are so many different glass companies centered in this area of the country that one has to ask "why?"! This area was fundamental in both the history of Pressed Glass as well as American Brillant Cut Glass.
The geology of the region supplied an abundance of silica, sand, coal and natural gas, all the necessary components to the glass making industries. Abundant, low cost energy resources, excellent river transportation and a very skilled and ready work force made it possible for numerous glass manufacturers, both large and small, to exist.
Having access to the large supply of sand (silica) from nearby Lake Michigan some of the glass of this period, such as that used in Mason jars has the characteristic blue color.
Companies such as Cambridge, Central, Lancaster, Imperial, Hocking, Fostoria, Owens-Corning, Tiffin, Libbey and many other notables have their roots in this area. The smaller companies would over time be consolidated into U.S. Glass, National Glass or another conglomerate.
The companies frequently exchanged molds, sold their blanks to the same cutting houses in the area, leading to many of the popular patterns being attributed to more than one leading manufacturer.
The glass patterns in the beginning were "lacy" to hide the imperfections of the glass. Over time, as the process became more refined the patterns produced took on a geometric feel.
Of the many different patterns produced, only a handful have found their way to being reproduced. Generally, reproductions are heavier than original issues and have a slick or "oily" feel whereas old glass feels "dry" & sharp.