If finalized, she will succeed outgoing Rep. Ed Royce (R-CA), chairman of the House Foreign Affairs Committee.

"I thank everyone who supported me and all the volunteers," Kim said at an election night watching event in Rowland Heights, just after her election appeared certain. "This was possible thanks to the Korean community's support."

She gave credit to Royce for helping her "more than 100 percent" and pledged to work hard as a bridge between South Korea and the US.

But she also noted that she wasn't elected just for the Korean community and may not be able to serve only their interests.

"Only when I succeed in mainstream society can I return the favor (to the Korean community)," she said. "Because I am Korean, I will make sure to return more than you expect."

In addition to working to improve bilateral relations, Kim said she will work to resolve issues impacting the local Korean community, including trade, immigration, reunions with family members in North Korea, and campaigning for Korean women who were forced into sexual slavery for Japanese soldiers during World War II.

The only other Korean-American to serve in Congress was Jay Kim, a Republican who represented California's 41st district from1993 to 1999.

Young Kim worked for Royce for two decades, first when he was a state senator and then in Congress. Her last role was as director of community operations and Asian affairs.

She herself was elected to the California legislature in 2014.

After immigrating to the US territory of Guam in 1975, Kim moved to Hawaii and then to California, where she attended the University of Southern California.

She later ran several businesses.

Her congressional district, which includes parts of Los Angeles, Orange and San Bernardino counties, is two-thirds Asian and Latino.

Despite being traditionally Republican, the district was won by former Secretary of State Hillary Clinton, a Democrat, in the 2016 presidential race.

Kim has distanced herself from some of President Donald Trump's policies, including his hard-line stance against immigration.

In New Jersey, another Korean-American and Democrat, Andy Kim, was in a tight race against incumbent Republican Rep. Tom MacArthur in the 3rd congressional district.

With 99 percent of the ballots counted, the former adviser to former President Barack Obama won 48.9 percent of the vote, trailing behind MacArthur's 49.8 percent by only 0.9 percentage point, according to the AP tally.

The final result is expected to be out in several days after adding on the absentee votes and ballots cast at six remaining polling stations. Those stations are located in areas that are statistically more in favor of Kim.

The 36-year-old worked as director for Iraq issues on the Obama administration's National Security Council, and enjoys the former president's strong backing. (Yonhap)