UPDATE: Donald Trump's attempt to have thousands of election votes in Nevada thrown out has failed.
The suit claimed that some of the state's polling places had stayed open as much as two hours later than they should have, in order to allow more people to vote.
Those votes could be central to the result in Nevada, which is a swing state key to any potential victory by Mr Trump.
If successful, the lawsuit would have asked that records of thousands of early votes would be discounted. But the judge said that the case was "disturbing to me" and make clear that she was "not doing it".
Long lines kept polls open past the 7 p.m. posted closing time at locations that included a Mexican market and several shopping centers. Officials say at one site, the last voter cast a ballot after 10 p.m.
The case could be just the first of a range of potential lawsuits, since Mr Trump is expected to challenge results that don't go his way if they are close.
State Republican Party chief Michael McDonald had criticised the decision to leave voting open for longer than had been expected, suggesting that it had been done to allow hispanic people to vote.
"Last night, in Clark County, they kept a poll open until 10 o'clock at night so a certain group could vote," Mr McDonald said at a Sunday rally for Trump.
"The polls are supposed to cose at seven. This was kept open until 10. Yeah, you feel free right now? You think this is a free and easy election? That's why it's important."
But Democrat Hillary Clinton's campaign is dismissing the Nevada case in a Twitter message, calling it "a frivolous lawsuit."
Under election law, anyone who is in the queue to vote must be able to cast their ballot, even if that happens after the scheduled close.
KTNV political analyst Jon Ralston has said that the huge interest from hispanic voters has probably meant that Donald Trump has lost that state.
Claims of rigging or other problem voters have blighted the election process this year, with claims of voter suppression being made by both sides.