From Philly dot com:
It was a simple walk from her seat to the front of the Society for the Advancement of Judaism, a New York City synagogue. But when 12-year-old Judith Kaplan was summoned by her rabbi father to read from her Bible and recite some blessings, the act was revolutionary.
On a March Saturday in 1922, two years after women in America got the right to vote, Rabbi Mordecai M. Kaplan broke tradition. He had, in essence, held a coming-of-age ceremony for his daughter, what boys at 13 had celebrated for centuries.
Of course, what Judith performed was not, in fact, identical. She didn’t read directly from the Torah, nor would the ceremony afford her the same synagogue privileges as males. But it did mark a giant step toward religious equality. Ninety years ago this month, it was the first American bat mitzvah.