The average age of potty training in the 1950s was around 18 months of age.
Nearly 92 percent to 95 percent of kids were potty trained and out of diapers by age 18 months of age.
In the 1950s kids potty trained earlier than they do now because kids in the 1950s wore cloth diapers and not disposable diapers like they do now.
The cloth diapers and plastic pants that kids and babies wore in the 1950s were uncomfortable when wet and it motivated kids to get out of the cloth diapers much sooner.
The cloth diapers also required more frequent changing and washing to ensure that the child or baby had an ample supply of cloth diapers and they were kept clean.
Due to the extra work required to cloth diaper kids in the 1950s, parents were also more motivated to get their kids out of diapers and using the toilet much sooner.
Today though kids mostly wear disposable diapers which are very absorbent and with most disposable diapers, kids don't really feel wet and they don't often mind being in the wet or dirty disposable diaper.
Changing disposable diapers and just simply throwing the disposable diapers away after use also makes it less motivating for parents to potty train their kids.
It's often more convenient and easier for parents and caregivers to just change disposable diapers than deal with potty training and all the accidents.
Some kids will also eventually potty train themselves by age 3 or 4.
But if they don't then most kids still will often be potty trained by 2 to 3 years old.
Potty training also often differed in the 1950s and involved encouraging or forcing the child to sit on the potty until they peed or pooped.
But today, modern potty training is a more child readiness approach.
The shift to later potty training also began in the 1960s and was driven by Dr. T. Berry Brazelton who promoted the Pampers diapers and also with the introduction of disposable diapers and he said that you shouldn't rush toilet training and they will do it on their own.