Fashion is defined as the prevailing clothing style during a particular time. That definition suggests that fashion changes over time. What makes a dress or an accessory trendy is not rocket science. But how do trends emerge?

Trends have no single source. Their origins can be traced to movies, street culture and social movements. Industry professionals say artistic creativity flourishes when people take risks, are open-minded and determined.

How many people need to be wearing a yellow skirt or haute scrunchies before they can be called fashionable? In many cases what matters is who is wearing them. Styles can become trends when mass media publications, start writing about them.

The advent of the movies in the early part of the last century made people more aware of style and trends, and the increasingly affluent middle class could aspire to look like film stars. As a result entertainers became fashion influencers.

But how can you tell if it’s a trend or a fad? If it keeps evolving and crosses over from one group of consumers to another over a period of time, then it’s a trend. If it doesn’t progress after it first became popular, then it’s a fad. (Think butterfly hairclips and wallet chains.)

The following list is a selection of Americans who have had tremendous influence on what people wear, despite not being fashion designers themselves. You will not see names such as David Bowie and The Beatles on the list because they were not American, even though they influenced fashion trends all over the world, including the United States.

Click here to see America’s most popular fashion influencers.

Michelle Obama
> Period of influence: Since 2009

Michelle Obama set several trends during her eight years in the White House. One of them was the sleeveless dress. Known, among many things, for her toned arms, the former first lady started the sleeveless trend as early as 2009 when she wore a white one-shoulder chiffon dress at Barack Obama’s inauguration. After that, the sleeveless dress became her go-to fashion choice.

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Elizabeth Taylor
> Period of influence: 1970’s

Although born in England, Elizabeth Taylor is on this list because she was born to American parents and lived most of her life in the United States. The Hollywood icon was known for her love of jewelry, especially big diamonds. One of the most famous pieces is the 33.19-carat diamond ring given to her by Richard Burton. An auction of her jewels took in $116 million in 2011, more than doubling the record for a single collection.

Jane Fonda
> Period of influence: Late 1980’s

Jane Fonda became known as an exercise guru after her original workout video was released in 1982. The famous actress’s five best-selling aerobic videos also set a trend in fashion. Leg warmers, which she claims to still have, became an instant hit. Leg warmers and leotards become standard wear for women who were working out.

Grace Kelly
> Period of influence: Late 1950’s

Grace Kelly was known for her elegant, sophisticated fashion choices. The Hollywood star turned princess made the Hermès bag popular in 1956 when she used it to hide her baby bump. Ever since then, the small bag with straps has been known as the Kelly bag. It has been making a comeback, with prices going up 350% in the last decade and popularity surging in 2016.

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Marilyn Monroe
> Period of influence: 1950’s

Marilyn Monroe is credited with combining sex appeal and fashion. The Hollywood icon was known for wearing clothes that emphasized her feminine curves — such as high-waisted bikinis (with heels) and red lipstick. She didn’t wear loose clothes and she made her hips stand out with a tiny waist and large bust.

Madonna
> Period of influence: 1980’s

The list of trends Madonna started is long — conical bras, tutus, and too much jewelry — but the one that is making a comeback these days are the colorful haute scrunchies. Now that they are in vogue again, some are even ridiculously expensive, ranging from $110 to $810.

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Bella Hadid
> Period of influence: Since 2017

Small sunglasses were a thing in the late 90’s, but the Hadid sisters, who along with their mother are sometimes called the first family of fashion, are bringing them back. You often see Bella Hadid with the micro frames, whether she is wearing gowns or sweat pants. While Selena Gomez and Kendall Jenner have also been spotted wearing small sunglasses, Hadid made the fashion news with her choice of a pair that was so small they barely even covered her eyes.

Jackie Kennedy
> Period of influence: 1960’s

The little pillbox hats Jackie Kennedy wore in the 1960’s were not expensive designer hats. The most famous pillbox hat in history is perhaps the one that was part of the pink Chanel suit she was wearing when President John F. Kennedy was assassinated in 1963. The former first lady was also known for loving pearls and white gloves.

Lauren Bacall
> Period of influence: 1950’s

As an actress and TV show host, Lauren Bacall became known for her fashion choices, earning the nickname “The Look.” One of her most popular looks was the tan subway coat. The camel-color cashmere coat was plain and simple on the outside but lined with matching sequins on the inside. Student curators at The Museum at the Fashion Institute of Technology created an exhibit showing the late actress’ most iconic looks.

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Michael Jackson
> Period of influence: 1980’s

Everyone knows Michael Jackson’s red jacket from the 1983 “Thriller” video. Before that it was the red leather “Beat It” black power jacket in 1982. And who can forget the smash hit “Bad” video from 1987 and the moto jacket he wore. The power jacket became one of the the King of Pop’s most iconic clothing items.

Farrah Fawcett
> Period of influence: 1970’s

Farrah Fawcett may have started the feathered-hair revolution. If there is one thing people remember about the “Charlie’s Angels” actress, it’s her hair. The classy cool-looking layers were what every woman wanted. Decades later, there are still dozens of Farrah Fawcett hair tutorial videos on YouTube.

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Dorothy Hamill
> Period of influence: 1970’s

When Dorothy Hamill won Gold in the 1976 Winter Olympics and the World Championships the same year in figure skating, everybody wanted to have short and bouncy hair like hers. The wedge haircut became an instant fad. In her autobiography, Hamill said she liked the simplicity of short hair — “wash ‘n’ wear” style. She still wears her hair the same way.

Ariana Grande
> Period of influence: Since 2016

Ariana Grande’s signature look is her ponytail. The singer is credited with a spike in demand for hair extensions in Australia. But beauty can be painful. Grande has admitted on Twitter that her high and very tight ponytails are a source of constant pain due to the amount of extensions piled up.

Josephine Baker
> Period of influence: 1920’s

Josephine Baker was the face of the art deco movement in the 1920s. The American expat in Paris was among the most famous and respected entertainers in Europe. Her fashion choices were as famous as her dancing — large gold baubles, pencil-thin eyebrows, slicked-back hair, flamboyant feather, and bold makeup.

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Lady Gaga
> Period of influence: 2010’s

Raw meat as a dress, disco ball head accessory, corseted lace dress and a gold mask, red latex dress and glitter eye decals (when meeting Queen Elizabeth), gravity-defying shoes…these are just a few of Lady Gaga’s daring outfits through the years. It’s hard not to wonder what the self-proclaimed Mother Monster will wear on her next night out.

Beyoncé
> Period of influence: Since 2013

When it comes to performing on stage, one thing doesn’t change. Beyoncé’s signature style on stage is a one-piece bodysuit that is flashy, shiny, and covered with jewels, embroidered or inset with lace.

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Kim Kardashian
> Period of influence: 2010’s

Millennial pink is the hottest trend these days. The popularity of the subdued pink can be traced back to the Kardashian clan. When perhaps the most famous of them, Kim Kardashian, started wearing neutral, skin and nude tones, fashion trends followed.

Kylie Jenner
> Period of influence: Since 2015

Plump, pouty lips are a thing now because of Kylie Jenner, who got her first lip filler when she was 16. The trend even has its own hashtag — #KylieJennerLips. The look consists of defined cupid’s bow and overlined edges. Jenner’s Lip Kit line and cosmetics are the reason she is called the youngest self-made billionaire in the United States.

Johnny Depp
> Period of influence: Late 2000’s

Johnny Depp is the not the first guy to wear eyeliner (Green Day’s Billie Joe Armstrong and Jared Leto, for example), but he is the most famous, especially in the hit role of Captain Jack Sparrow from the “Pirates of the Caribbean” movies. The so-called guyliner was such a signature look that some people thought he was sick when photos of him not wearing it surfaced.

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Diane Keaton
> Period of influence: Late 1970’s

Diane Keaton set a trend for women wearing trousers when one of her most famous movies, “Annie Hall,” came out in 1977. She turned the trouser-suit into a high fashion statement. Katharine Hepburn was also known for wearing high-waisted pants, but they never became as popular as when Annie Hall became a household name.

James Dean
> Period of influence: 1950’s

James Dean is the embodiment of casual style. White t-shirt with jeans and a black leather jacket (and hair slicked back, which was popular in the 50’s) was his signature look — and his daily style.

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