Sen. Elizabeth Warren (D-Mass.) greets the overflow crowd before a roundtable discussion in Storm Lake, Iowa, on Saturday. (Brian Snyder/Reuters)

Art Cullen is the editor of the Storm Lake Times in Northwest Iowa. He also is the author of the new book “Storm Lake: A Chronicle of Change, Resilience, and Hope from a Heartland Newspaper.”

Rural America is lost to Democrats, or so the saying goes.

So why all the long lines snaking around the block waiting to touch the cloak of Sen. Elizabeth Warren (D-Mass.), that scion of the liberal left — a law professor from Massachusetts, no less — on the West Coast of Iowa last Saturday?

She started in Council Bluffs, a tough meatpacking town lurking in the shadow of brighter Omaha. She packed them into the Orpheum Theatre in downtown Sioux City, where the stockyards are long gone, for a barn-razing speech. Tear down the corrupt house that sucks your fortunes to the centers of wealth and power, she said, an exhortation as old as the railroads. The senator stopped in Storm Lake, my hometown, to a crowd of about 200 graying enthusiasts and one Trumpist heckler in a Lynyrd Skynyrd shirt who whacked a Warren supporter with a selfie stick and was tackled into an evergreen tree by the assistant police chief. No need for the Secret Service here.

The others were enthralled. It was the biggest political gathering since Hillary Clinton swung by in 2008, when she filled our middle school gym.

But why would Warren launch here? Iowa’s Democrats live east of Interstate 35 in places such as Dubuque, Waterloo and Davenport, the old union tractor factory towns. She did hit the capital city of Des Moines for a rally, but the statement of where she started was unmistakable: No ground will be ceded.

“If Democrats are going to build a grass-roots movement, they have to go where the people are — all the people, not just some,” Warren told me Saturday. “I grew up in Oklahoma. Your main drag looks like mine in Wetumka. The core values we shared are the core values that Americans believe in — they want their kids to have a fighting chance to build a future here.”

That sort of language resonates as two-thirds of our counties, all rural, wave goodbye to the young every year. Iowans are fleeing those places for bigger cities such as Des Moines-Ames and Cedar Rapids-Iowa City, our metro-state university corridors. Those places are solidly blue and growing. Iowa State University economist Dave Swenson notes that county seats and other regional trade centers of 10,000 to 30,000 people are losing people ages 31 to 44 who have acquired skills and would be the ones to have children in school, vote for bond issues, serve on the city council, and moderate the poles of politics between left and right.

Meanwhile, the small rural towns will never be the same. They used to have labor unions. They don’t anymore. They used to have shopping malls. They are going vacant. Most have a community college that can turn out welders, who earn $18 per hour. And they used to have college graduates. When the young people leave now, the schools left behind are weaker, the elderly and unskilled are stuck in place, and a politics of resentment can fester. The exodus started last decade and continues this decade, Swenson says, and the movement is inexorable.

Warren says it has been going on 40 years or more, since at least the Reagan Revolution.

Everywhere she went last weekend, Warren led with her story of humble roots: a father who was a janitor and couldn’t support the family. Pregnant at 21, she got on track in community college and ended up a law professor and the bane of Wall Street banks as head of the Consumer Financial Protection Bureau.

She said the chemical companies are poisoning the water and destroying farms and rural communities. She lumps Big Ag in with Big Oil and Big Pharma and the Chicago Board of Trade. It’s a familiar song in a region that gave rise to William Jennings Bryan. They lapped it up Saturday, so frustrated they are from long neglect. She is running against the same system that Donald Trump railed against, except she says that the root is corruption.

The caucuses 13 months away are expected to winnow the Democratic field and show who can get voters to go out and sit for a couple of hours in a school cafeteria on a February night.

Warren answered that question with those lines around the block, willing to wait outside to hear some of that old-time religion of populism. Left or right, it sells out here.

Read more:

Art Cullen: The key to winning Iowa in 2020

Dalibor Rohac: Why 2019 will be a tough year for populists

Megan McArdle: Populists on the left and right might want to think twice about cheering on the norms-busters

Terry McAuliffe: To beat Trump, Democrats must counter his lies with realistic solutions

Alexandra Petri: You may already be running