On the opposite end of the ideological spectrum, Kentucky’s libertarian senator, Rand Paul, has proposed a more supply-side-oriented strategy: Let certain counties eliminate capital-gains taxes and institute a special federal income tax of 5 percent in those areas. “I’m just letting you keep more of your own money,” Paul said to a small crowd in a college auditorium in eastern Kentucky last winter. “The difference between this and a government grant is I don’t choose who gets it.” On either side of the aisle, the underlying assumption is the same: Places like Clay County just need a kick-start. But what if that isn’t true?

In many cases, a primary problem in poor rural areas is the very fact that they’re rural — remote, miles from major highways and plagued by substandard infrastructure. Think about the advantages of urban areas, described by thinkers going back to Jane Jacobs and beyond. Density means more workers to choose from, more potential customers, more spillover knowledge from nearby companies. As such, cities punch above their weight, economically speaking. The 10 largest metro regions produced more than a third of the country’s entire economic output as of 2012.

The converse is true for rural areas. Take eastern Kentucky, grappling with the decline of coal — and perhaps looking at an even bleaker future for the industry, given recent carbon-reduction efforts by the E.P.A. Those rolling hills might be picturesque. But those country roads make it hard to ship goods in and out, in turn making it more expensive to build a warehouse or a factory.

“One of the challenges that faces eastern Kentucky is the remoteness of the area,” said James P. Ziliak, the director of the Center for Poverty Research at the University of Kentucky. “It’s difficult to get to a lot of places. The communities are small, and they’re spread apart, so you lose that synergy that you want to spark development a lot of times.” Even with additional government subsidies, would businesses really want to move there? “It’s this chicken-and-egg problem,” Ziliak said. “My view is that firms will never locate into a community with an unskilled labor force, unless the only labor they need is unskilled. And there has been a historic lack of investment in human capital in these areas.”

The queasy answer that economists come to is that it would be better to help the people than the place — in some cases, helping people leave the place. Generally, the wealthier and better educated the family, the more mobile they are. It takes resources to pack up all your things, sign a new lease, pay for gas or a flight and go. That might help explain why more Americans aren’t flocking from places with high unemployment rates to places with low ones, even if those places are surprisingly close together. College graduates, for instance, are several times as responsive to differences in labor demand as those who completed only high school, according to a study in The Journal of Human Resources.

But government policy based less on place and more on people might help ameliorate that trend. “Let’s say I was a hardworking person who lost my job in Harlan, Ky. — the ideal place, really, to go is Williston, N.D.,” Senator Paul said. “People need to be mobile to go there. Some government programs prevent mobility or discourage mobility.” And none encourage it: There are scant federal resources to help the unemployed or the poor in rural areas move to a job or even just a better neighborhood. (Imagine Senator Mitch McConnell running for re-election on the campaign slogan: “I’ll get you out of this moribund area and up to the wilderness of North Dakota!”)

Of course, thousands of families in places like Kentucky, South Dakota and West Virginia manage to cobble together enough resources to make the move themselves; the share of Americans living in rural areas has slowly drifted down. In Clay County, the population has declined for the last decade. And the overall population in rural areas declined for the first time from 2010 to 2012, according to the Census Bureau.