Historically, the race is over before South Dakota hold its primary election. But this year voters there could still have a voice if the race between Clinton and Barack Obama continues for another month.
Clinton said if she drops out of the race then South Dakota voters won't have a say.
"I've been looking forward to making this stop in South Dakota because I think it's real exciting that you're going to be able to cast your vote and it's going to count in picking the nominee for the Democratic Party," she told a crowd of about 1,000 at an airport hangar.
South Dakota and Montana hold primary elections June 3 - the last in the nation. South Dakota has 23 delegates up for grabs.
Clinton pressed her major campaign themes in a 40 minute speech, stressing a need to change energy policy and work on creating more renewable energy. She said the part of the country from the Dakotas south to Texas is known as the Saudi Arabia in wind production.
"If we harness the wind coming off these plains and we had an electric grid system with a distribution system to transmit it from right here in South Dakota across our country we would be moving toward clean, renewable energy," she said. "We should set a goal of 25 percent of our energy to be renewable by 2025 and invest right here in South Dakota."
Clinton said oil companies should be made to put ethanol pumps at gas stations.
Campaign workers pressed those in the crowd to register to vote as Democrats. There were stations to assist in the paperwork.
Evaleena Stotts is a registered Independent. She's not eligible to vote in the primary unless she does switch. It's something she's considering. She said she came to see what Clinton had to say.
"She's straight to the point and strong, really strong," she said. "She's not just the rhetoric, and she has a lot of experience."
Democrats in South Dakota could get more attention. Barack Obama's campaign says he'll make a stop in South Dakota. The state party is trying to host a debate between the two candidates. Some in the crowd disapproved of Democratic Party elder statesman George McGovern's withdrawal of his endorsement.
The timing of McGovern's announcement that he was switching his allegiance to Obama - on the eve of Clinton's Sioux Falls visit - made it even worse, said Sandra Duncan, of Luverne, Minn.
"I'm terribly unhappy with George McGovern," said Duncan, who gave McGovern a ride to the airport in 1968 after a Robert F. Kennedy campaign visit.
McGovern wasn't the only noticeably absent Democratic leader, as most other high-ranking South Dakota politicians from the party have come out in support of Obama. Clinton was introduced by Malcom Chapman, a Rapid City councilman.
Terri Jones of Brookings, Duncan's daughter, said the McGovern switch hurt South Dakota's chance to make a difference in the campaign.
"He's disenfranchised South Dakota voters. With the late primary we have, this counts for something," Jones said.
Clinton has campaigned in the state with her husband, Bill Clinton, and was in Lennox in 1994 to pitch a health care plan.
Former Republican candidate Rudy Giuliani visited Sioux Falls in November, and the presumptive GOP nominee, John McCain, was in the state in October 2006.
Jones, Duncan and others at the airport hangar said they think the U.S. needs change but that Clinton has more experience to accomplish that change than Obama.
"The country is in a lot of trouble right now and I don't think that he's given solutions," Jones said.
Alicia Dorothy, 23, of Harrisburg, said she has been a Clinton supporter since childhood and never considered backing anyone else this election cycle.
"There's something about her, her charisma, her demeanor and how strong she is, and her thoughts and views," she said of Clinton.
Her husband, Matthew, 24, a business consultant, said Clinton is the better candidate because of her health care policy. She has focused it and improved it since her 1994 visit, he said.
"It's probably a lot more defined," Matthew said.
Matthew Dorothy's parents, Charles and Donna Dorothy of Sioux Falls, also showed up, not knowing that their son and his family were in the crowd.
Donna Dorothy, 56, said it's time for a woman president. Clinton has an advantage because of her experience, she added.
"We kind of liked the way Bill did things," Donna Dorothy said.
Voters know lots about Clinton, but that's not the case with Obama, she said.
Matthew Dorothy said that's important to him, as well. "Her experience is one of the largest (reasons) for me. The problem I see with the platform of change is, I don't know if he (Obama) has the clout to bring about that change."
Sisters Gabriella and Francesca Collignon of Sioux Falls also attended the rally. There's no way Clinton should drop out of the race, Gabriella Collignon said.
She said she thought about supporting Obama but believes Clinton is much better qualified. "I think it shows a lot about her personality that she's going to keep going."
Terri Jones' daughter, Nikki, who just finished her freshman year at South Dakota State University, said having a woman president would help her generation break through the glass ceiling that still remains.
As for Obama, she said, "I think guys tend to go for Barack Obama because they don't think a woman can handle it."
Asked whether her friends support Clinton or Obama, Nikki Jones said, "They're all pretty much Republicans."
Chimed in Sandra Duncan, "If you're a Democrat in South Dakota, you're already a minority."
The chairman of the South Dakota Republican Party, Karl Adam, said in a statement that Clinton is too liberal and out of step with South Dakotans.
"Her priorities just aren't South Dakota's priorities," he said.
The last Democratic presidential candidate to win South Dakota was Lyndon Johnson in 1964.
(The Associated Press contributed to this report)