A History of Bicycle Helmets
A History of Bicycle Helmets
streets.mn A History of Bicycle Helmets and a Study of Bicycle Helmet use in Minnesota
Kids wear them most, then women, then men. Bicycle helmets go back to the 1880s, and they’re more common among recreational riders.
By no means is this exhaustive and it's from 2017, but I found it really interesting.
And this site says that the cheapo helmet from a few years ago is still just as effective as a new expensive one.