For nearly a decade, the photographer John Moore has traversed the Mexico-United States border, covering the story of immigration from all sides — American, Mexican, immigrant and border agent.

His depiction of the border is both literal and figurative.

He captures misty images of river bends and rusty walls that undulate over sun-bleached grass, the natural and man-made lines of defense. He also makes intimate portraits of both migrants and border officers who square off on either side.

Migrants are splayed out on cold concrete floors, huddled beneath sparse tree cover as border agents circle in helicopters above, and lined up in a row, handcuffed, illuminated by the blue lights of police vehicles.

Law enforcement becomes a part of the landscape — rigid and unyielding, as fixed as the walls, mountains and infrastructure they patrol. They survey stunning patches of forest and farmland with rifles at the ready. They listen stone-faced as racial epithets are shouted at anti-immigration rallies.

But for Mr. Moore, immigration begins and ends well beyond the physical border — a line where fear and hope collide to shape American politics.

Mr. Moore’s border drops down to the gang-controlled neighborhoods of Honduras, where violence and insecurity are forcing record numbers of families to flee. It stretches north for hundreds of miles, from the auburn deserts of Arizona into the farmlands of Colorado, where migrant workers grow and harvest organic kale.

A young mother decides the odds of surviving a 1,000-mile trek to the United States are better than those of staying home, and her family’s journey begins. For some, their travels end in a locker containing the personal effects of “unknowns,” remnants of the anonymous. For others, there are white body bags.

Mr. Moore chronicled the journey of immigrants, bringing together a body of work that involved dozens of trips over the years but came into focus after the election of Donald J. Trump, when American frustration over illegal immigration found its mark.

A few days after the election, Mr. Moore was on a plane back to the border to continue shaping what would eventually become a book.

Since Mr. Trump’s election, the numbers of migrants trying to cross into the United States has dropped, though historically they remain high. Many attribute this drop to Mr. Trump’s rhetoric and a hostile climate in the United States.

But wherever the numbers go, Mr. Moore’s images reflect an American truth: The fury and debate over immigration to the United States appears to be going nowhere.