Los Angeles, California - Rihanna joked that she'll "sneak into the polls" and vote with her son's passport as she encouraged Americans to vote on Election Day.

The Grammy-winning singer, who was born in Barbados and has not changed her citizenship, shares two-year-old son Rza and 15-month-old son Riot Rose with Asap Rocky.

Rihanna shared a video of herself looking out of a car window on Instagram, captioning it: "Me trying to sneak into the polls with my son's passport."

The 36-year-old used the hashtag #votecauseicant.

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The Fenty Beauty founder is the latest celebrity to weigh in on the upcoming election, with a host of famous faces throwing their weight behind Democratic presidential nominee Kamala Harris.

Taylor Swift, who previously described the current vice president as a "steady-handed, gifted leader," also urged people to vote as she wrapped up her Eras Tour shows in the US.

Meanwhile, Rolling Stones frontman Mick Jagger said his children would be voting for Harris.

Alongside photos of him with six of his eight children, the 81-year-old wrote on Instagram: "Don't forget to vote – Jagger kids are voting for Kamala."

Harris has harnessed star power as she focused on battleground states in her bid for the White House, with Beyoncé, Eminem, Bruce Springsteen, Jennifer Lopez, and on Monday, Lady Gaga, among those to have appeared at her campaign events.

Polls have opened across large swathes of the US, with well over 80 million people having already cast their votes in an election expected to be historically tight.