They were told to not express their opinions too strongly -- it's not polite. To not challenge a man -- it's not ladylike.
For those girls -- many of them now mothers with daughters of their own -- what happened Tuesday night was more than a political triumph.
Regardless of party persuasion, Hillary Clinton's victory is the definition of historic: She became the first female presidential nominee of a major political party.
Her chances of becoming president -- the first woman head of state in America's 238-year history -- are now much closer to reality.
"When I was a kid I was never told, 'You could be president one day.' My brothers were," Emily Dreyfuss, a writer with Wired magazine, tweeted Tuesday. "I could be an actress, a teacher, a mother, a writer!"
Be what you want to be
The impact of the moment was not lost on Clinton.
Before she took the stage to a euphoric victory rally, she posted two photos to her Instagram page.
The first was a picture of her in a hallway with a little girl.
"To every little girl who dreams big: Yes, you can be anything you want—even president. Tonight is for you," the presumptive Democratic presidential nominee said.
The second was her going over her speech, pen in hand. The caption simply read: "Ready."
Clinton: My mother was my role model
On stage, Clinton talked about the role her mother played in shaping her future. Dorothy Rodham was born the day Congress passed the 19th Amendment -- which allowed women to vote.
"My mother believed that life is about serving others. And she taught me never to back down from a bully -- which it turns out was pretty good advice," Clinton said.
"I wish she could see her daughter become the Democratic party's nominee."
There's a choice
To many, Clinton's nomination is an encouraging sign of a more inclusive America.
Scott Bixby, a reporter for the Guardian, summed it up succinctly -- emojis of a series of white faces followed by a black emoji and then a woman's face. He titled it: "Democratic presidential nominees, pictured."
To be sure, Clinton still has to duke it out with Donald Trump to win the presidency. But many mothers across the country said that for her to even reach this point is an uplifting example to young girls.
"Alalys and Mirabella will both be of age to vote this year," one woman posted on Instagram. "Regardless of who they vote for, the fact the they will have a choice to vote for a women is beyond exciting!"
Fathers and grandfathers also celebrated.
"I just tucked in my daughter and told her that we can go vote tomorrow for President Hillary," one father said. "She said 'me too when I grow up!'"
Letting humor lead the way
In this age of social media where Twitter is the public barometer, not all sentiments were serious.
Some highlighted the historic win while also poking fun at it.
"ugh women presidents take so long to get ready," Alexandra Petri lamented, "literally 227 years."
And if Clinton wins the White House, what do we call Bill? First gentleman? First guy?
Sami Main's suggestion: "First dude."