I only wash my hair once a week, but then I can sit on it, washing it any more frequently makes it fall apart. When I was a child (and I'm only 37) it was not unusual for women with long hair to not wash it for two or three weeks at a time. Two hairdressers near us had a specific 'long hair wash' service!

Hair rinses involving egg whites used to be common in the 1940's and 1950's as they were an attempt to help the hair to recover from the perms used at the time. Beer was another. But these were rinses, not what you washed your hair with. Lye, carbolic and coal tar soaps were around by 1903. I think Pear's soap was as well.

I don't know about the U.S.A. but in Britain at this time there were many public bath houses. You went there to do your laundry and have a bath. Many people in London didn't have baths in their own homes well into the 1940's & 1950's. Our local public baths didn't shut down their actual baths until 1980 something, but the laundry and the swimming pool are still there.

I think what's more interesting is the difference between 1940 and now. That's mind boggling!