Editor’s Note: Photographer Callie Shell went backstage with Hillary Clinton on assignment for CNN at the 2016 Democratic National Convention. The opinions expressed in this commentary are hers.

Philadelphia CNN  — 

Twenty-three years ago, I was a newly hired White House photographer, working for Vice President Al Gore, attending a staff welcome party held by first lady Hillary Clinton. She announced at the event that she was changing the rules. Women would be allowed to wear pants.

At first I thought she was joking, but I quickly learned that women had not been allowed to wear pants up to that point.

On Thursday night, I photographed Clinton backstage as she changed another rule about the White House, accepting the Democratic presidential nomination to become the first female to be nominated as a major party candidate in the United States.

I watched as Clinton listened to her daughter Chelsea, who was out on stage, from the holding room. The former Secretary of State appeared tense, but not nervous. She was focused, aware of the weight this speech had on others, and I don’t mean the effect the speech would have on her candidacy, though I’m sure she was aware of that too. I mean that she knew it was an important moment for women in this country.

Backstage, alone, and then in the holding room with her family, staff and friends, Clinton seemed to be a person who, no matter what happens the next few months, and on this night at least, had already won the race of a lifetime.

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During the benediction.
During the benediction.
Backstage after accepting the presidential nomination, Clinton embraces campaign chairman John Podesta as another top aide, Huma Abedin, stands nearby.
Backstage after accepting the presidential nomination, Clinton embraces campaign chairman John Podesta as another top aide, Huma Abedin, stands nearby.
Clinton thanks her staff for their work on her campaign.
Clinton thanks her staff for their work on her campaign.
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A fist bump with Jake Sullivan, Clinton's top policy adviser.
A fist bump with Jake Sullivan, Clinton's top policy adviser.
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Clinton talks to Cheryl Mills, who has worked with Clinton since her White House days and was her chief of staff at the State Department. Mills now serves as an adviser to the campaign.
Clinton talks to Cheryl Mills, who has worked with Clinton since her White House days and was her chief of staff at the State Department. Mills now serves as an adviser to the campaign.
Clinton hugs civil rights leader and U.S. Rep. John Lewis.
Clinton hugs civil rights leader and U.S. Rep. John Lewis.
Clinton celebrates with her husband, former President Bill Clinton; her running mate, U.S. Sen. Tim Kaine; and Kaine's wife, Anne Holton.
Clinton celebrates with her husband, former President Bill Clinton; her running mate, U.S. Sen. Tim Kaine; and Kaine's wife, Anne Holton.

Callie Shell was the official White House photographer for Vice President Al Gore from 1993-2001. After 2001, she became a contract photographer for Time magazine. This is her seventh campaign and her sixth Democratic National Convention. Her photographs have been published in books, newspapers and magazines and exhibited worldwide.