President Trump’s feckless trade war is bludgeoning the bottom line of the Republican Party’s reliable rural base. But the party’s disregard for the economic interests of its own constituents goes well beyond barriers to Chinese markets.

Small towns and rural areas, along with some Rust Belt metros, are falling ever further behind booming urban dynamos — leaving many heavily Republican regions in a deepening morass of economic deterioration, joblessness, substance abuse and declining life expectancy. The lower-density places most Republicans call home produce barely half as much wealth as our biggest cities — and it’s showing.

Yet the travails of America’s struggling red regions, and practical ideas about might be done to alleviate them, are barely mentioned in right-leaning policy circles. For example, “The Once and Future Worker,” a widely discussed book by Oren Cass, a former economic policy adviser to Mitt Romney now at the Manhattan Institute, focuses on initiatives to expand employment and wages for American workers but largely neglects the changing geography of economic output and opportunity behind the woes of heartland workers.

Worse, the Republican Party under Mr. Trump has blundered into a positively anti-rural economic agenda, leaving the soybean fields littered with $20 bills for enterprising Democratic presidential hopefuls to pick up. The president’s nativist immigration agenda deprives farms and small factories of workers local economies can’t otherwise supply, while the administration’s latest budget proposal continues the Republican assault on the health care and social insurance programs rural populations increasingly rely on to survive.