The West Texas backdrop for the fictionalized bank heists in “Hell or High Water” couldn’t be more different from the Boston locations of the true events behind the Boston Marathon bombing of “Patriots Day,” yet production designer Tom Duffield approached both stories the same way: He strove for accuracy.

Scottish director David Mackenzie looked to Duffield to supply a dusty decor for the modern Western, telling the designer he “didn’t know much about the American West” and was relying on him to “make it right.”

“We actually went on a scout through West Texas to see where Taylor Sheridan based the script,” says Duffield, “but due to a limited budget, producers wanted to shoot in New Mexico [to take advantage of the tax rebate]. I had to figure out how to deliver that same look in an entirely different state.”

The crew shot in a handful of New Mexico towns, including Moriarty, Estancia, Clovis, and Portales, to illustrate the small-town life where two brothers, played by Chris Pine and Ben Foster, go on a spree of holdups to save their family ranch. “I channeled Martin Ritt’s 1963 ‘Hud’ to stylize the dusty, decaying look,” says Duffield. “We wanted wide-open expanses with soft gray-greens, brown hues, and earth tones to create the feeling of desolation.”

A tiny, white house stood in for the family ranch. Duffield added a back bedroom where the brother’s mother stays during her dying days, and a windmill to the front yard. “The window screens were ripped; everything was aged,” he says. “We wanted it to feel like it was lived-in to the maximum.”

To cement the film’s realism, the designer used an actual working bank and its tellers in Post, Texas, for a shootout scene. And for the climactic sequence set on a ridge, Duffield and location manager Jonathan Slator hiked for weeks to find the exact spot. “It had to come right off a road so the truck could drive up the embankment, and it needed to have a higher elevation on one side so he could shoot down from it,” notes Duffield. “Ben was great — he got the truck further up the hill than the stunt guys.”

In Peter Berg’s “Patriots Day,” Duffield stretched the budget to build an exact 1,000-foot replica of Boylston Street, where the terrorist bombing occurred.

“We visited all the real locations to match everything exactly. The same granite, the same bricks and concrete — everything down to the gum spots on the street,” Duffield recalls.

At a South Weymouth, Mass., air base, construction crews built the two main areas where the Boylston Street explosions occurred — the storefronts, the bleachers, the photo bridge, the barricades, and the finish line right down to the flags. Two store interiors were also completely re-created, one for the Marathon Sports store, the other for the Forum restaurant. Boston-based Zero VFX filled in the rest using visual effects.

“These two movies, in terms of budget and crew size, couldn’t have been more different,” Duffield says. “But when you have directors that trust you, it allows you to give them your best.”