Based in Omaha, the company operates the largest rail network on the continent, a conduit that provides us with cereal, lumber, car parts and pretty much everything that touches our lives. That makes the railroad a real-time barometer of the fluctuations in global trade — a physical manifestation of how President Trump’s agenda to remake the rules of commerce will play out.

Roughly 40 percent of the goods that Union Pacific moves touch an international border at some point in their journey, putting the railroad at the center of the global tensions that have arisen as the administration prepares to impose tariffs on goods from China and steel and aluminum from around the world. Seventy percent of rail freight between the United States and Mexico travels on Union Pacific trains, meaning the outcome of the tense renegotiations for the North American Free Trade Agreement will shape the company’s future.

“At its guts, a railroad like Union Pacific is built on people consuming stuff, industry consuming stuff, and trade flows,” said Lance Fritz, Union Pacific’s chief executive. “When those are happening and growing, we thrive. And all of that potentially gets impacted by getting Nafta wrong or the United States exiting Nafta.”