Please note that my interest lies only in the "helmet design", by which I basically mean the shell and faceguard colors, the logo decals (if any), and the stripes running over the top of the helmet (if any). No attempt is being made here to illustrate the physical variations of helmets produced by different manufacturers, or the many different styles of faceguards, nor do I intend to show changes in the physical structure of helmets over the decades (at least not in the near future); partially for these reasons, 1960 has been somewhat arbitrarily chosen as the cut-off date for all the historic helmets for now. I am also not attempting to display fine details like "award decals" that would not show up well in the image size I am using here, or those details that would not be visible from this perspective (such as numerals on the back of the helmet). It is not my intention to illustrate every variation worn by every individual football player on any of these teams, just whatever was "the" design for each team at a particular time.
Link, via Archaeoblog (!)