BISMARCK, N.D. - In making a documentary about how the nation votes, actress Kirsten Dunst and filmmaker Jacob Soboroff were drawn to North Dakota, the only state without voter registration.

"It's different than any other state in the United States, and what we're looking at is best and worst (voting) practices," Soboroff said Monday. "I don't know if it's a best practice or ... a worst practice, and that's why we're here."

Soboroff and Dunst, who has starred in three "Spider-Man" movies, are directing and producing a documentary, not yet titled, that explores why American voter participation lags behind turnout in most other countries.

"What we're looking to do is give a nonpartisan look around the United States, and around the world, at how people are affected by voting systems, and what that means to the voters," Soboroff said.

They interviewed the state's chief elections officer, Secretary of State Al Jaeger, on Monday, and said they planned to interview other North Dakotans on Election Day.

Dunst and Soboroff met in July when Soboroff was taping an election commentary for National Public Radio. Soboroff is the director of Why Tuesday? - a nonprofit organization that researches ways to increase voter turnout.

Dunst, 26, said she offered Soboroff some performance tips and became interested in the organization's goals.

"The older you get, it makes you feel more and more responsible for the power you have, especially being in the entertainment industry ... and how delicate and important it is to use that power to influence people in a positive way," Dunst said.

Soboroff said he and Dunst are working with Participant Media, which produced "An Inconvenient Truth," a documentary on global warming that features former Vice President Al Gore.

Dunst said she plans to narrate the documentary but doesn't know yet whether she will appear in it. Soboroff and Dunst have already voted; they cast absentee ballots Oct. 20 in the Los Angeles County registrar's office in Norwalk, Calif.

"Being a part of this is constantly teaching me new things," Dunst said. "I feel totally honored and was really proud to vote, and have never been so proud to vote in my entire life."

North Dakota doesn't require people to register to vote. Voters must bring a photo ID issued by the state, military or an American Indian tribe, a recent utility bill that lists the voter's residential address, or sign a sworn statement attesting that they are eligible to vote in their precinct.