There are three distinct chapters to the history of the American derailleurs in this collection.
The first chapter relates to the ‘ten speed years’ from 1960 to 1980 - a period during which the American bicycle market and industry remade the bicycle world. This is largely the story of Schwinn, but also includes Excel.
The second chapter is that of the CNC machine shops that briefly burst on the scene in the mid 1990’s producing beautifully crafted and frighteningly expensive derailleurs for mountain bikes. Within a few years these derailleurs had all faded away.
It is notable that, unlike Europe, the first American derailleur here only dates from the 1960’s and that, in SRAM, America has a viable active manufacturer alive today. Perhaps heritage is not all it's cracked up to be.