WILLIAM BRANGHAM: The Rockettes are one of the most iconic dance groups in the country, and they're celebrating a big anniversary this year.

The "News Hour"s Julia Griffin explains.

JULIA GRIFFIN: In New York City this time of year, holiday cheer and twinkling lights are easy to spot.

But of all that shimmers, perhaps nothing sparkles more than 36 rhinestone Rockettes high-kicking their way through the "Radio City Christmas Spectacular."

The longest-running precision dance company in America, the Rockettes are not only celebrating the holiday season this year, but also 100 years on stage.

Founded in St.

Louis in 1925, the troupe was originally known as the Missouri Rockets.

But, by 1933 they'd moved to New York, settled into their Radio City Music Hall home, and launched the annual "Christmas Spectacular," changing their name to the now famous Rockettes along the way.

A mainstay of American entertainment, the Rockettes have performed at presidential inaugurations, Super Bowls, and countless lightings of the Rockefeller Center Christmas Tree.

Today, the company is 84 members' strong; 36 dancers grace the stage each show, kicking some 200 times each before the curtain closes.

Some members dance with the group for more than a decade.

JULIE BRANAM, Director and Choreographer, "Radio City Christmas Spectacular": It's just really a magical thing being a Rockette.

JULIA GRIFFIN: "Radio City Christmas Spectacular" director and choreographer Julie Branam was a Rockette herself for 13 years and knows what it takes to grace the Radio City stage.

JULIE BRANAM: I think it takes incredible dancing, number one, and a willingness to work harder than you have probably ever worked at any other job in your life, because you have to really want to look like everybody else and put in the time and effort to do the precision work.

JULIA GRIFFIN: That precision work, a sharp, synchronized mixture of jazz, tap, and ballet, is a style almost unique unto itself and one that binds Rockettes, past and present, in a unique sisterhood.

AUDREY MCDONALD, Rockette Dancer: Joining this legacy that's been inspiring audiences for generations is just so special and it's such an honor.

JULIA GRIFFIN: Current Rockettes Audrey McDonald and Courtney Crain grew up in Louisiana together.

COURTNEY CRAIN, Rockette Dancer: This is my fifth season, but experiencing it now through her eyes and her first season, it's really magical for me and special for me.

JULIA GRIFFIN: For 11-year veteran Megan Kelley-Crocco, a core memory was learning one of the numbers that has been in the show since 1933.

MEGAN KELLEY-CROCCO, Rockette Dancer: When I first learned "Parade of the Wooden Soldiers" 11 years ago, I had -- that was my moment of, oh, my gosh, I'm a Rockette.

So many women have done this number before me and now I get to do it and I get to share this with the people I love and inspire more generations of future Rockettes out there.

JULIA GRIFFIN: And over the years, the Rockettes have shared secrets on how to keep the friendship strong.

WOMAN: For the Rockette hookup, our right hand is high on the woman next to us and then our left hand is low.

And we never touch.

That's the last thing you want to be doing is hitting your neighbor while we're doing these kicks.

WOMAN: That's a good way to lose friends.

WOMAN: Yes.

(LAUGHTER) JULIA GRIFFIN: This year, to mark the group's centennial, the Sixth Avenue street sign outside Radio City Music Hall was renamed Rockettes Way.

And... WOMAN: Once a Rockette, always a Rockette.

(CHEERING) JULIA GRIFFIN: ... more than 500 past and present Rockettes from all 50 states and several countries celebrated the troupe's legacy on opening night.

SUSAN DUSTIN, Former Rockette: Radio City has a unique ability of really honoring the women that came before us and paying tribute to the past, while incorporating all of the modern-day things.

And we remain today to be the world's most famous dance troupe.

And so it's just extraordinary.

JULIA GRIFFIN: For PBS News, wishing you a high-kicking happy new year, I'm Julia Griffin.