A day after her historic upset win to take Illinois’ 14th Congressional District seat, Lauren Underwood credited women and young voters with propelling her to flip a once reliably Republican district.

“People like to talk about our community as this very red area. So many entrenched conservatives,” Underwood said Wednesday while thanking staffers and volunteers at her campaign headquarters in St. Charles. “I think we have completely turned that on its head.

“Our race proves that what people had previously written off can’t be written off anymore,” she said.

Underwood, a 32-year-old African-American nurse, took 52 percent of the vote against four-term incumbent GOP Rep. Randy Hultgren, making her the first woman — and the first black person — ever to represent the overwhelmingly white district, which spans the far north and western suburbs out to rural areas.

The Naperville resident joined a host of other “blue wave” Democratic candidates across the country who flipped historically conservative districts to wrest House control from the GOP.

The 14th was drawn to favor Republicans, encompassing DeKalb, DuPage, Kane, Kendall, Lake, McHenry and Will counties. No Democrat had been elected to the seat since Bill Foster a decade ago, and before that, now-disgraced former Republican House Speaker Dennis Hastert held the seat for two decades.

Underwood will become just the fourth Democrat to hold the seat in more than a century.

Illinois 14th Congressional winner Lauren Underwood talks with volunteers and supporters of her campaign at her headquarters in St. Charles, Ill., Wednesday, Nov. 7, 2018. (John Starks/Daily Herald via AP) ORG XMIT: ILARL204

Illinois 14th Congressional winner Lauren Underwood talks with volunteers and supporters of her campaign at her headquarters in St. Charles, a day after the election. | John Starks/Daily Herald

“I think there had been a lack of investment [by the Democratic Party]. Folks had decided that maybe this was not a winnable community,” Underwood said. “But all the raw resources were there.

“We certainly had broad appeal among conservatives, independent and liberal voters,” Underwood said. “We also expanded the electorate and engaged people who had never voted before. We engaged women and young voters.”

The Naperville native said she was “stunned” to sweep every county except McHenry, where she said the gap was about 2,000 votes.

“That had been unheard of in the 14th District,” she said. “Even the most rural parts of our district. … We were present in those communities, and we have seen the fruits of that type of investment. It has far exceeded even my expectations.”

Underwood, often referencing her own chronic heart condition on the campaign trail, honed in on health care reform in the final weeks before the election, while Hultgren tried to appeal to his conservative base by trekking downstate to appear onstage at a campaign rally with President Donald Trump.

Underwood said she decided to run for office in 2016 after taking part in the Women’s March in the wake of Trump’s election.

“Women are superheroes. Moms of the 14th District run every PTA, every neighborhood association, every church group. They run civic organizations. They just haven’t necessarily run for office at the same level in the past. And this year it’s changed,” she said.

“What’s happened this year is that women across the country have seen that there is a way to step forward and lead, and there are millions ready to support you.”