The Clintons voted at 8 a.m. at a local elementary school.
Hillary, whom pollsters have given a slight edge over rival Republican Donald Trump in the elections, told reporters the event was "humbling".
Attired in a cream and taupe leather blazer, Hillary shook hands and hugged voters.
People crowded around her with cellphones, taking photos as she cast her ballot.
Speaking to media afterwards, Hillary was more subdued than at her celebrity-filled rallies on Monday night, reported The Guardian.
"It's a humbling feeling
…because I know how much responsibility goes with this," she said.
"So many people are counting on the outcome of this election, what it means for our country and I'll do the very best I can if I'm fortunate enough to win today," she added.
Bill Clinton, when quizzed about how it felt to be a political spouse, said, "It's been that way for several years now, and good."
"I've had 15 years of practice," he quipped, laughing as he walked away, the daily reported.
