Production of this tool was started in 1928 in, I believe, Chicago. Skils original model saw was called the Michel Electric Hand Saw Which later came to be called the Model E. Skils own website provides a nice overview of their history. There is a lot of info on the history of the company itself, but very little on the progression of tool models through the years.
I haven't really had much luck tracking the history of Skils early tools. This is what I believe to be an first generation model 77 Skilsaw. Find great deals for Vintage Skilsaw Model 77 Worm Drive Saw 1 Owner Mag 7 1/4' Magnesium SKIL.