Kansas voters have chosen to uphold abortion rights in the first electoral test of the deeply polarizing issue since the US Supreme Court allowed states to ban the procedure outright.
Voters overwhelmingly said they did not wish to amend the state constitution to assert there is no right to abortion.
If the ballot had gone the other way, lawmakers could have moved to further restrict or ban abortion in the state.
Michigan, Arizona, Missouri and Washington also held elections.
These states saw Senate races that could determine which party controls the upper chamber of Congress next year, and two of the nation’s most hotly fought races for governor.
Tuesday’s elections were also a test of former President Donald Trump’s influence in the Republican party as he hints of a possible third run for the White House in 2024.
The vote in Kansas – a referendum separate to the congressional and gubernatorial elections – was the first statewide electoral test of abortion rights since the US Supreme Court two months ago overturned Roe v Wade, the 1973 ruling that legalised the procedure nationwide.
The result will be seen as a potential barometer of the issue’s resonance ahead of nationwide mid-term elections on 8 November, with Democrats fighting to retain control of Congress.
Kansas officials said voter turnout across the state was significantly higher than expected on a primary voting day when Republicans usually outnumber Democrats by two to one.
Although Kansas is deeply conservative, its abortion regulations are less strict than many other Republican-led states.
It allows pregnancies to be terminated up to 22 weeks with other restrictions, including a mandatory 24-hour waiting period and mandatory parental consent for children.
The legislature of the Great Plains state is controlled by Republicans, but its politically vulnerable governor, Laura Kelly, is a Democrat, who favours abortion rights.
More than a dozen Republican-led states have moved to ban or further restrict abortion since the Supreme Court decision on 24 June.
But 10 states across the US, including Kansas, have the right to abortion protected in their state constitutions, provisions that can only be overturned through referendums like Tuesday’s.
Other states, like California and Vermont, are holding votes in November to add protections to abortion in their state constitutions.
Tuesday’s elections were also being viewed as a litmus test of Mr Trump’s sway over the Republican party.
He endorsed a slate of candidates who have amplified his unsubstantiated claims that he lost the November 2020 presidential election because of mass voter fraud.
In Michigan’s governor’s race, Trump-endorsed media personality Tudor Dixon won the Republican primary to take on Democrat Gretchen Whitmer in November.
Vote counts were ongoing for other Trump-backed candidates, including Arizona Senate candidate Blake Masters and Arizona governor candidate Kari Lake.
In Missouri, Attorney General Eric Schmitt comfortably beat scandal-plagued former Governor Eric Greitens.
On the eve of the vote, Mr Trump had announced his endorsement for “Eric”, but his spokesman did not clarify which one he meant.
Results are still expected in the primary elections for three Republicans who voted to impeach Mr Trump last year.