Republicans and Democrats make vastly different contributions to the U.S. economy, according to a new Brookings Institution study.

In the 2020 election, Brookings found that the 2,497 counties across the country that voted for President Donald Trump generate 29% of the U.S. GDP. Meanwhile, the 477 counties won by President-elect Joe Biden contribute 70% of the American economy.

According to the study’s lead author, Mark Muro, a reorientation of the economy, in addition to a relocation of a portion of the American population over the past 20 years, accounts for the growing division between the two parties’ economic interests.

“Clearly, the ascendance of an education-driven, urban-oriented, professional services economy over the last 20 years is a huge driver,” Muro said. “So, if nothing else were happening, we would see the rising importance in terms of GDP of these big urban counties…But also people weren't staying in the same place. The last 20 years have also seen a steady out-migration from an anemic, small town, rural economy.”

At the same time as densely populated urban areas such as New York City or Silicon Valley have become home to the nation’s biggest drivers of economic growth—the financial services, tech, and professional services industries—major trends in the global commodities markets, the growing recognition of the impact of global warming, and automation have taken a hit on the large swaths of rural America that rely on agriculture, fossil fuel production, and manufacturing, respectively, as the bases of their economy, according to Muro.

Add in the “brain drain” that has seen many educated people flock to the cities away from outlying counties, and you have a pretty clear picture as to why urban areas have prospered at the expense of rural communities over the past two decades.

And, of course, any electoral map will tell you that the nation’s geographic division has mirrored its political division: Whereas a diverse set of college-educated people tend to both reside in metropolitan counties and vote blue, less-educated, white workforces that back Republican policies largely represent the country’s small town, rural communities.

Muro did acknowledge that some Republicans may work in metropolitan counties themselves—and thus contribute to their GDP—but live full-time in outlying counties, which could make the GDP statistic appear more lopsided than it is in reality. Still, Muro remains extremely concerned with the increasing divide between the economic interests of Republicans and Democrats. For context, in the 2000 presidential election, the winner carried counties that represented just 54% of the U.S. GDP.

“So we now have this extreme political gridlock that aligns with this very deep economic divide,” Muro said. “That's what's so worrisome. It used to be that the manufacturing economy, for instance, was both urban and rural. It's now mostly rural, and you're hard-pressed to find a manufacturing city. By the same token, it's pretty hard to find early-stage software development in rural America. The alignments here have made the problem more difficult.”

Muro believes the key to realigning interests between urban and rural America is to “make sure that more heartland states are anchored by dynamic, middle-size metros.” Investing in technological infrastructure, job training, and education in heartland America will be essential to both reinvigorating rural economies and preventing future brain drain, Muro said.

As it currently stands, the counties Trump carried in the 2020 election are not just worse off with regards to GDP contribution, they also suffer from lower employment growth and lower average household income levels than their urban counterparts. If we can’t develop a solution that closes the gap between the interests of urban and rural, Democrat and Republican, then Muro worries the country will face an existential crisis.

“On the one hand, we can see a fading of U.S. preeminence because this is no way to manage and advance a globally competitive national economy,” Muro said. “So that's the most encouraging thing anyone could say. The worst you could say is that you do actually have backlash, some kind of actual violent rejection or divide—some kind of secession.”