Any farmers who have a loan with the Farm Service Agency will have the agency’s name on any checks they get in the mail for sales of grain or cattle. Now no one at the agency can sign their name on those checks, and they can’t be deposited until that happens. Those farmers can’t get money to pay bills.

Farmers who are in financial straits can’t apply for a guaranteed loan from their local bank, because they have to look for F.S.A. concurrence when decisions are made on one. When banks can’t get the confirmation, farmers can’t get loans.

Money isn’t moving, and when farmers aren’t moving their money, whole towns suffer. Thousands of towns. All across America.

Mark White has been farming for 40 years. His farm, which his brother rents and operates, is just south of the county line, near Williamson, Iowa, population of approximately 150. Mr. White works with Smith Fertilizer and Grain, a full-service fertilizer, feed supplier and grain-receiving facility.

“The biggest problem is immediate cash flow,” he said. “It doesn’t necessarily mean that they are broke — or headed out of business — but they are having to use some equity that they have built up over the years to survive a downturn like we are in.” Using equity, he said, means putting land or equipment up as collateral against operating notes, or past operating notes they can’t pay off. He says this can be risky and is “taking a step backward.” Younger farmers and farmers who rent and don’t own land are more at risk.

These less secure farmers with cash flow problems are the ones most at risk during the shutdown because they can’t cash F.S.A. checks or get loans. Farming for most is a losing proposition already because of low commodity prices — the tariffs and shutdown hurt even more. Many Americans can’t afford to lose their monthly paychecks — and that includes farmers. My banker friend tells me we lost a generation of farmers because of the farm crisis of the 1980s, and if it gets much worse, she fears we could see it again.

Most rural American farms are not big corporate operations. The most recent available farm census data, from 2012, shows that Iowa has nearly 89,000 farms, and 57 percent are small farms under 180 acres. Generally, to make a living on farm income, operations of at least 225 to 750 acres or more are needed. Of the farmers that Mr. Trump’s tariffs and shutdown are hurting, about 80 percent are family businesses.