Sarah McBride is to become the first transgender state senator in the US after she won her race in Delaware.
She beat Republican Steve Washington to take over the seat from Democrat Harris McDowell, who is standing down.
Ms McBride, 30, has worked as the press secretary of LGBTQ advocacy group the Human Rights Campaign and was a trainee in President Obama's White House.
She is one of a handful of candidates who has made history in a nail-biting night across the country.
"I hope tonight shows an LGBTQ kid that our democracy is big enough for them, too," Ms McBride tweeted after her win.
Ms McBride is not the only transgender candidate to make history during the election. Vermont's Taylor Small, 26, was elected to the House of Representatives, while Stephanie Byers made history in Kansas as the first trans person of colour to ever be elected to a state legislature.
In Oklahoma, Mauree Turner became the first ever non-binary candidate to win a seat in a state legislature.
And in New York, Mondaire Jones and Ritchie Torres won their seats and became the first black openly LGBTQ people ever elected to Congress.
"Mondaire and Ritchie have shattered a rainbow ceiling and will bring unique perspectives based on lived experiences never before represented in the US Congress," Annise Parker, of the LGBTQ Victory Fund, told Pink News.
Other historic firsts
Meanwhile, Republican Madison Cawthorn won in North Carolina to become the first member of Congress born in the 1990s.
Mr Cawthorn turned 25 - the qualifying age for Congress - in August. He faced controversy over sexual misconduct allegations during the campaign.
And after she comfortably won her seat in Georgia, Marjorie Taylor Greene was labelled by US media as the first elected politician to have expressed support for the QAnon conspiracy theory.
QAnon is a wide-ranging, unfounded conspiracy theory that claims US President Donald Trump is waging a secret war against elite Satan-worshipping paedophiles in government, business and the media.
Ms Greene has promoted the conspiracy in online videos, but she tried to distance herself from the tile of "QAnon candidate" in an interview with Fox News earlier this year.
She spoke of finding "misinformation" in its theories and insisted she had chosen "another path".
The 46-year-old, who has been described by Mr Trump as a "future Republican Star", ran unopposed after her Democrat opponent dropped out of the race.
And a surprising second
Astronaut Mark Kelly won his race to be elected to the Senate - but he is not the first former astronaut to do so.
Former Ohio Senator John Glenn, one of the Nasa's first ever astronauts, took that distinction when he was elected in 1974.
Mr Kelly has personally logged 54 days in Space and has a twin brother, Scott Kelly, who is also a retired Nasa astronaut.
The senator-elect shared a photograph with his wife, former congresswoman Gabby Giffords, and thanked supporters for his win.