As she became not only the country's first female Vice President, but also the first Black and South Asian Vice President, Kamala Harris shone in a jewel-toned purple coat and dress by Black American designer Christopher John Rogers.
Hillary Clinton, who has served as both First Lady and Secretary of State, also donned a similar hue as she arrived in one of her trademark pantsuits designed by Ralph Lauren and former First Lady Michelle Obama made jaws drop in her plum coat and matching flared trousers and turtleneck by designer Sergio Hudson.
Though current First Lady Dr Jill Biden donned blue for the day's proceedings, the night before the inauguration she wore a striking purple coat by Jonathan Cohen Studio at the vigil for those who had lost their lives due to COVID-19.
So what was with the unofficial purple dress code?
Turns out there are a few reasons. First off, the colour purple is often associated with royalty and with no king or queen, the President and their partner are something of an equivalent.
“Our democracy came out of a monarchy and colonial situation. We've never had our own royalty so we tend to project that desire,” Gwendolyn Dubois Shaw, senior historian of the Smithsonian’s National Portrait Gallery noted.
It also reflects the theme of the Biden Harris inauguration (America United) and is the resulting colour when Democratic blue and Republican red are mixed.
"We must end this uncivil war that pits red against blue, rural versus urban, conservative versus liberal," Biden said in his first presidential address.
Purple is also the colour of the Purple Heart, the badge of honour and bravery bestowed to veterans injured or killed in the line of duty by the United States military.
Though everyone at the inauguration was bundled up in wintry coats, down here in the Southern Hemisphere it isn't exactly chilly but there are some stunning purple pieces you can add to your wardrobe.
Whether you need new pieces for work or a summery dress as we enjoy the last months of warm weather, we have you covered when it comes to the season's most symbolic colour.
This Jimena Tie Knit Dress is a chic option for work or even play when dressed down with sandals or sneakers and comes in at just $59.
Adding a little bit of opulence into your workwear is easy - the Concise Silk Bow Tie Blouse is soft and comfortable as well as stylish.
It's made of 100 per cent silk and you'll feel like fashion royalty in it. Hillary Clinton would approve.
If you fancy embracing your inner Michelle Obama, get her look with the Ex-boyfriend Aubergine Blend Oversized Jacket just in time for winter.
The price has also been slashed down to $189.95 so it's the perfect investment for the colder months.
As for those who prefer something a bit more casual but still love that purple hue, the Magnolia Dress is for you.
It's timeless so you can wear it every time you have a spring/summer event too.