The two main US political parties parted ways for the third stage of the surprise-filled race for the White House, with the Democrats heading west and the Republicans campaigning in the south.
In Nevada, CNN, Fox News and NBC News called the contest for the former secretary of state. With roughly two-thirds of precincts reporting, Clinton was at 52.2 percent to 47.7 percent for Sanders.
"To everyone who turned out in every corner of Nevada with determination and heart: This is your win. Thank you," Clinton tweeted.
In the desert state of Nevada, both Clinton and Sanders worked hard to reach out to the African-Americans, Hispanics and Asian-Americans who make up roughly half of the state's population.
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Clinton, who won by a hair in Iowa but was crushed by Sanders in New Hampshire, was counting on a major Hispanic voter turnout, especially among Las Vegas hotel and casino employees.
Nevada has some three million residents, and the population is overwhelmingly concentrated in two large urban centers, Las Vegas and Reno.
Clinton won their first showdown in Iowa on February 1, but only by a razor-thin margin.
Since Wednesday, the 68-year-old Clinton has visited staff at casinos in Las Vegas, where workers "caucused" right on the famous Strip.
"I need your help this morning -- in the show room, 11 am," she told employees at Harrah's yesterday, less than an hour before caucus time. Sanders visited the same casino cafeteria about 20 minutes earlier.
The former first lady and senator from New York has relentlessly attacked Sanders for voting against immigration reform in 2007.
Sanders counters that the measure gave little protection for foreign "guest workers," and that he voted for a 2013 immigration reform bill that died due to Republican opposition.