U.S. Secretary of State Hillary Clinton and Sen. Barbara Mikulski (D-MD) make a few remarks at FORTUNE Most Powerful Women Dinner at U.S Department Of State's Benjamin Franklin Diplomatic Room on April 30, 2012 in Washington, D.C.
Paul Morigi—Getty Images
By Ryan Teague Beckwith
Updated: March 2, 2015 12:16 PM ET

The legislative legacy of six-term Sen. Barb Mikulski, who announced Monday she would retire in 2016, is long. The longest-serving woman in Congress, the Maryland Democrat has had a hand in everything from health care to the budget, sponsored the Lilly Ledbetter Fair Pay Act and helped bring female senators to work together.

But one of her signature achievements is also so mundane today that it’s hard to appreciate: Thanks to Mikulski and former Republican Sen. Nancy Kassebaum, women can wear pants in the Senate.

Here’s how it unfolded, according to a 2011 story from Capitol Hill publication Roll Call:

Mikulski later told CNN that the pants-wearing was a “seismographic event.”

“The Senate parliamentarian had looked at the rules to see if it was OK,” she recalled. “So, I walk on that day and you would have thought I was walking on the moon. It caused a big stir.”

These days, when former Secretary of State Hillary Clinton is able to joke about her “sisterhood of the traveling pantsuit,” it’s hard to appreciate the importance of Mikulski’s rebellion. But as Clinton herself noted testily once, male politicians are rarely asked which fashion designers they wear.

Pantsuits are practical, they’re apolitical and they save time and mental energy. President Obama once told Vanity Fair that he only wears either blue or gray suits so that he can save his decision-making for weightier matters.

The pantsuit leveled the playing field for Clinton and other female politicians, and they can thank Mikulski for it.

Contact us at editors@time.com.

SPONSORED FINANCIAL CONTENT

Read More From TIME

EDIT POST