Families were large in the early 1900's, and although many kids shared a bed, there was still a mountain of sheets waiting to be wash with whatever frequency the housewife could manage! In the city, manufactured soap could be purchased. In rural areas, the homemaker might have to make her own from ashes and lard.
Such a labour intensive process!
And can you imagine the damage lye soap and washboards could do to the hands?
Here is a link to Niagara minis blogpost which describes this project.
http://niagaraminis.blogspot.ca/search/label/Laundry
