He went to a ballot drop-off location outside of the Chase Center in San Francisco at the facility's "Thrive City" area.
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"We're trying to make it easy as possible. And to have easy access," said Kerr, an eight-time NBA champion.
He also greeted fans.
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The drop-off location will be open through Election Day on Tuesday.
A Warriors facility in Oakland and the arena of the "Santa Cruz Warriors" are also being used as polling sites and drop-off locations.