Written by Noelle Mateer, CNN

Delving into the archives of pop culture history, "Remember When?" is a new series offering a nostalgic look at the celebrity outfits that defined their eras.

Remember when pantsuits were controversial? There were hard and fast "rules" about where and when you could wear them. In the office, yes. In an official portrait for a first lady, never. That is, until Hillary Clinton came along.

Paintings of her 20th-century predecessors show a parade of cream-colored gowns, strings of pearls and periwinkle skirts. Clinton rocked a pantsuit in midnight black.

The official portrait was unveiled in 2004, three years after she had left the White House, but by then we all knew what was dominating her wardrobe.

Today, Clinton's penchant for pantsuits is so well-known that it's spawned think pieces, memes, Saturday Night Live jokes and Halloween costumes available for purchase on Amazon.

By the 2016 US presidential race, die-hard fans wore pantsuits to the polls to show solidarity with the Democratic hopeful. It spawned a hashtag #PantsuitNation and a Facebook page where supporters shared their own experiences of society's pushback against what the pantsuit ultimately represents -- equality.

White House Collection/White House Historical Association

Clinton was an early adopter of the pantsuit as an outward sign of her ambition to level the playing field for men and women. She went to great pains to distinguish herself from other first ladies, emphasizing her career and law degree, rather than simply her role in relation to her husband.

During Bill Clinton's first presidential run in 1992, Hillary made headlines when she was caught on camera saying: "I suppose I could have stayed home and baked cookies and had teas, but what I decided to do was to fulfill my profession." She apologized to homemakers while on the campaign trail for weeks afterwards.

The quote sparked controversy, but it was also accurate: Clinton had a policy agenda, and she was actively working toward its passing.

As first lady, she chaired the Task Force on National Health Care Reform, pushing a proposed healthcare system some in the media dubbed "Hillarycare." That failed, but she found more success with 1997's State Children's Health Insurance Program, and then the Adoption and Safe Families Act, and the Foster Care Independence Act.

She worked with the National Institutes of Health to ensure more funding for asthma and prostate cancer. She did not, in short, stay home and bake cookies. Evidence of her own career is visible within the official portrait itself: Her book, "It Takes a Village: And Other Lessons Children Teach Us," lies on the table beside her.

The Clintons portraits are unveiled in the East Room of the White House in June 2004. Credit: Mark Wilson/Getty Images

The pantsuit reflects that she did not think of herself as a first lady, but rather a politician. In her 2017 memoir, "What Happened," Clinton wrote about the inspiration behind her favorite outfit, noting simply that she "thought it would be good to do what male politicians do and wear more or less the same thing every day."

In subsequent years, when Clinton was a politician independent of her husband, the meaning of her pantsuit shifted.

When she was a congressional, and later presidential, candidate, critics saw her outfit as an attempt to hide her own femininity, as if she could trick us into thinking she were a man with leg holes alone.

Some poked holes through what they determined to be a "newly-lowered voice." Social scientists' research shows that this likely "wasn't helpful" to her professional success -- people have been known to distrust women who veer from gender norms.

Ultimately, Clinton lost the big election.

But as the President-elect took to the podium, Clinton sent a very clear message to her supporters, once again through her pantsuit. It was stylish, tailored and white, the color of the suffragists.