Blake Lively Explains Why She Joined the Women's March in Touching Instagram Post

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Blake Lively proudly joined the Women's March on Saturday, and is telling fans why participating in the movement was so important for her.

The 29-year-old actress marched in New York City, and Instagrammed a picture of herself next to a little girl in a wheelchair holding a sign reading, "Let's make American kind again."

"I marched for my daughters, for my friends, for strangers, for myself, for Phoebe here in this picture who I met as she motivated everyone she came across," Lively wrote. "My march wasn't driven by hate. It was rooted in a very simple fact -- we are all equal. I believe everyone can agree on that. Thank you to everyone who marched all over the world. I felt so hopeful and deeply grateful. #whyimarch."

WATCH: Natalie Portman Calls Out Trump During Moving Speech at L.A. Women's March -- 'You Just Started the Revolution'

Lively is of course referring to her daughters with husband Ryan Reynolds, 1-year-old James and 3-month-old Ines.

The Shallows actress was reunited with her Sisterhood of the Traveling Pants co-star Amber Tamblyn at the march, where they posed for a cute selfie together.

WATCH: Beyonce Speaks Out in Support of Women's March on Washington -- 'We Can Make Our Voices Heard'

Their fellow Sisterhood of the Traveling Pants co-star America Ferrera was also at the Women's March in Washington, D.C., where she gave a rousing speech to the well over half a million people in attendance.

"Our dignity, our character, our rights have all been under attack, and a platform of hate and division assumed power yesterday," Ferrera said. "But the president is not America. His cabinet is not America. Congress is not America. We are America. And we are here to stay."

Watch the video below for more on Ferrera, Madonna and Scarlett Johansson's powerful speeches.