President Bush won nearly 70 percent of the county's vote in both 2000 and 2004, but the standard of living here has declined steadily during his administration.
The farm equipment factory that employed 500 workers here is closing. So is the milk plant. Farmers are facing skyrocketing feed and fertilizer costs, and gas prices are squeezing household budgets of those who now have to drive elsewhere for work.
Nationally, Bush won almost 60 percent of the rural vote, but Republican John McCain doesn't appear to be doing as well.
In an AP-Yahoo News Poll in June, rural voters favored McCain over Obama, 40 percent to 34 percent. About 34 percent of rural voters said McCain "shares my values," compared to 27 percent who said Obama did.
Recognizing an opportunity, Obama has opened more offices in rural areas than any other Democratic presidential candidate in years, pushing a message focused on job creation. Neighborhood campaign teams have been going door to door talking about Obama and his economic policies. In Ohio, his campaign recently announced a "Barns for Obama" effort, in which farmers are encouraged to paint their barn with Obama's logo.
Economy is hardly the only issue, here as elsewhere.
Religion and race are still powerful forces in rural America, and whether Obama can gain ground in traditional rural safe havens for Republicans could hinge on whether voters focus more on economic issues or cultural values when they go to the polls. Likability is also likely to be a strong factor.
Republican Barbara Dettloff, 72, a retired bartender from Racine, Ohio, an Appalachian river town with about 750 people, voted for Bush in 2004 and former Massachusetts Gov. Mitt Romney in this year's Republican primary. She's voting for Obama in November because "I think he's nice and I think he's sincere in what he says."
But, she added, "I'm probably the only person in this town that does."
Indeed, many of her friends have told her they're either not voting for Obama or are staying home. "They just won't vote for him because he's black," Dettloff said.
Some other rural voters like Carol Fuller, 45, of Lewistown, blame the Republican Party for their economic troubles but aren't ready to switch to a Democrat like Obama.
At the Belleville auction house on a recent day, Fuller described the future as "bleak." In part because of gas prices, she said she and her husband are living month to month on the farm where they raise poultry and cattle.
She accused the Republican Party of price gouging at the pump, mismanaging the Iraq war and failing to address health care. She said she would have voted for Democratic Sen. Hillary Rodham Clinton because she thought a woman could clean up Washington, but, as for Obama, "I just don't like him." She plans to vote for McCain.
Another farmer, Robert Thompson, 58, a Democrat and retired state worker from Millheim who raises cattle and hogs, said he still hasn't gotten over Obama's comments at a private San Francisco fundraiser that small-town voters in Pennsylvania are bitter and "cling to guns or religion." He said he's considering not voting for president because he doesn't like McCain, either.
If many rural voters follow the route Thompson is considering, it could hurt McCain in critical swing states, said Terry Madonna, a pollster and professor at Franklin & Marshall College in Lancaster.
"McCain will have problems getting a high turnout among those voters unless he finds some way to identify with them, some way to make them think that, A, he's not connected to Bush, and B, his economic plan is superior to Obama's," Madonna said.
He also needs to turn the conversation away from the economy, Madonna said, but "it's tougher to do that when times are bad."
Paul Lindsay, a McCain spokesman, said long-standing relationships Republicans have established in rural areas will pay off for McCain.
"John McCain continues to hear the concerns of rural families. ... That's why he has made every effort to engage these voters on his plans to create jobs and provide relief for working families," Lindsay said.
Says Dan Leistikow, an Obama spokesman: "We're getting a great response in rural communities that have been ignored by Washington and left behind in the Bush economy."
Mifflin is one of nearly 150 rural counties where the median household income has dropped by more than 10 percent since 1999, more than three times the national decline, according to an analysis by The Associated Press.
That could make a difference in traditionally Republican rural areas come November. In Ohio in 2004, for example, John Kerry might have won the state and the presidency had he won just 45 percent of the rural vote. As it was, Bush carried Ohio's rural voters by an almost 2-to-1 margin, according to exit polls.
Rural voters accounted for more than 10 percent of the total vote in all but three of 12 closely contested battleground states in 2004, and more than 20 percent in four of them - Iowa, Minnesota, New Hampshire and Wisconsin - according to exit polls. In all but two of the states, Bush won the small-town vote overwhelmingly.
The AP analysis of median household income was based on 2005 estimates, the latest available from the Census Bureau. In some of the rural counties heavily dependent on farming, income may well have rebounded since then, as rising soybean and corn prices have helped offset feed and fertilizer costs.
And not all rural counties are hurting. The median household income improved during the Bush administration in many rural counties near metropolitan areas.
But for counties like Mifflin, the recent economic decline is just a continuation of a trend that's lasted decades. Some of the county's economic woes date to 1972 when rains from Hurricane Agnes flooded parts of the area, including a profitable rayon fiber plant that was a major employer.
Tara Davidson, 36, a single mother and hair dresser from nearby Unionville, said she worries about what opportunities will be available for her 15-year-old son, who is already working to help out with their expenses. But she's not sure she'll even vote in November.
"I'm considering it, but I don't want any of them," Davidson said. "What if they get in there and make it worse?"