Avi:
Hate to burst your bubble, but this is NOT true:
“Until Torah uMasora was established after WW2 there were no day schools (all of the yeshivot you cite were for older boys – there was nothing for girls)”
The New Haven Hebrew Day School (now Southern CT Hebrew Academy) started classes in 1944
My brother-in-law’s eldest sister was enrolled in the first class. his next older sister and he attended through 8th grade. He went on to a yeshiva in NY, and last June he retired after a career as a pulpit rabbi in Massachusetts.
Over the years, that school had a boys high school which closed, but has had a girls high school since the 1960s in continuous operation.