“We’re making a f—ing TV show here!”

Matthew Rhys’ booming stage voice, imbued with Welsh-accented gravitas, fills the commuter train sitting at the edge of the platform at a station in Tuckahoe, N.Y., about 18 miles north of Manhattan. “The Americans,” the beloved FX drama series starring Rhys and Keri Russell, is filming a pivotal scene for its series finale under extremely cramped conditions on a chilly March morning.

The train, borrowed from New York’s Metro-North Railroad, will move back and forth 2,000 feet for three-plus hours while “Americans” director-executive producer Chris Long and his team gather the shots they need.

Rhys, Russell and the rest of the crew are charged up to deliver a powerful conclusion to the six-season saga of the Soviet spy couple masquerading as Philip and Elizabeth Jennings, embedded as a typical 1980s suburban Washington, D.C., married couple with two kids, Paige and Henry. The critical adoration showered on the show has raised the stakes for Team Americans, led by showrunners Joe Weisberg and Joel Fields, to stick the landing with the final season that bows March 28.

The only hiccup on the Tuckahoe shoot is that the Metro-North conductor dispatched to help producers needs permission from a central dispatcher every time the train moves an inch. The authorization begins to take longer and longer between takes, and the delays are greatly concerning to the crew — Long calls it “torture” — as the clock ticks down on precious daylight lensing time.

Rhys’ declaration, delivered with mock anger and a broad smile, helps take the edge off the collective mood. Russell asks via the IFB radio if craft services has a bag of Fritos handy; it quickly complies.

Rhys and Russell’s spirit is notable because the shoot is taking place on March 4, the same day as the Academy Awards. Rhys co-starred in one of this year’s best picture nominees, Steven Spielberg’s “The Post.” But there’s no glamming it up in sunny Los Angeles for Rhys and Russell, who are a couple on screen and off. They’re hard at work in Spartan conditions on one of the last days of filming on a show that has been life-changing for both actors.

The wait between takes prompts some on the production team to nostalgically swap stories about their time on the show. A feeling of finality is in the air. Set dresser Kevin Leonidas recalls his first encounter with Rhys after joining the show in its second season. “I was working in the Jenningses’ kitchen, and I hadn’t met anybody yet,” Leonidas says. “Matthew walks up to me, shakes my hand and says ‘Hi, I’m Matthew Rhys.’ What star of a TV show does that?”

“The Americans” heads into its final season as a rare breed of series, even in the Peak TV sea of scripted dramas. Produced by Spielberg’s Amblin Television, Fox 21 Television Studios and FX Prods., the series has never been a big ratings draw for FX, but it has developed a fanatical fan base among TV critics and culture pundits, who have waxed on at length about its depth — “Nothing else can match its combination of genuine sadness and muted, mordant hilarity,” The New Yorker gushed in 2016. Yet it has never been an awards magnet. “Americans” broke into the top drama series race at the Emmys after its fourth season in 2016, only to be snubbed the next year. Rhys and Russell have landed Emmy noms for their work the past two years, as have Fields and Weisberg for writing. But they have yet to take home a trophy.

“The Americans” premiered Jan. 30, 2013, two days before Netflix ushered in the era of binge-watching with the debut of its first original series, “House of Cards.” The FX period drama soon got overshadowed by noisier and buzzier shows — “Breaking Bad,” “Mad Men,” “Game of Thrones,” “Homeland,” “Sons of Anarchy,” “Orange Is the New Black” — but it has endured as FX’s most consistently praised recurring series.

“This has been an incredible experience for me,” says Noah Emmerich, who co-stars as the dogged FBI counterintelligence agent Stan Beeman. “Americans” not only marked Emmerich’s first series regular role but also gave him the opportunity to branch out as a director. “Joe and Joel are incredibly open and collaborative and supportive,” Emmerich says. “They seem to take authentic pleasure from watching people grow.”

Weisberg and Fields, known on the show as “the Js” or “J&J,” set the tone from the start with a partnership forged out of an FX-arranged marriage.

When production on the series began in 2012, Weisberg was the CIA officer turned novelist turned TV writer who created the series. Fields was the seasoned TV pro who knew how to run a show. FX’s Eric Schrier, president of original programming, had a hunch Fields would be a good tonal fit with Weisberg. Amblin TV co-president Justin Falvey says the pairing was perfect. “They became like one hive mind,” he says. By all accounts, the two have worked as hard on making their professional relationship work as they have in plotting the ups and downs of the marriage that lies at the heart of “The Americans.” Weisberg calls Fields, the acknowledged master of process on the series, “the Albert Einstein of organization.”

Both men were well versed in the horror stories of battles on the set between creators and showrunners. The two went into the partnership with eyes wide open and a predisposition to talk through every issue imaginable. “We spent an absurd amount of time as we first got to know each other talking about how we were going to manage our relationship,” Fields says. “We traded sleep sometimes for talking about our process. It’s served our friendship well, and it’s really served our working collaboration well.”

That sense of common purpose has been instrumental in bringing a complicated period drama to life on a modest budget, by today’s standards. “Americans” in its final season costs around $4.5 million an episode, compared with the $6 million to more than $7 million price tag for many other cable and streaming dramas. That it’s a period work requiring special dressing for every scene and every extra makes what the show delivers on a beer budget that much more impressive.

“There’s a feeling that we’re working on something serious that means something,” says Weisberg. “I don’t think we’re creating world peace or anything, but it is a form of art. If you care about it, it’s a lot easier to come to work every day and treat the people around you well.”

A sense of mutual respect also emanates from the actors at the top of the call sheet, Rhys and Russell.

“They have a fantastic combination of genius talent, sheer human decency and work ethic,” says Fields. “They lead from a place of inner strength and outer collaboration. It’s a very special thing. There’s no episode where there aren’t several times when Matthew and Keri and their spirit on the set carries the crew through the final scene. They’re always there making everybody feel good about doing their best work.”

For FX, “The Americans” was simply too good to fail. Despite its modest audience, the show’s qualitative strengths, the harmonious set and the unusually efficient production process that Weisberg and Fields developed made it an internal favorite of FX Networks CEO John Landgraf and his programming team. It also was an early signal of a new business paradigm for the cabler.

“Just in the time that ‘The Americans’ has existed on our channel, we have moved from some ratings sensitivity about our shows to very little [sensitivity],” Landgraf says. “ ‘The Americans’ is a part of that journey. We make more money when we have a highly rated show, and ‘Americans’ has never been a highly rated show. But it has demonstrated enormous value for our business as a whole by virtue of its excellence.”

In the new world of infinite on-demand choice, the series looks to be heading down the same path as HBO’s “The Wire.” Its sterling reputation among TV connoisseurs has made it a strong performer for FX on VOD and streaming platforms. It’s the kind of seek-it-out stickiness that’s become the performance metric of the future.

Gavin Bond for Variety

“ ‘The Americans’ is a great story for our business,” says Schrier. “At a time when there’s a lot of auteur-driven television and big personalities and people being treated badly, this show is as good as it gets. This is a group of artists coming together to make something great.”

The seedling of what would become “The Americans” came to Amblin TV co-president Darryl Frank while he was traveling from Florence to Rome in a minivan on a family vacation in June 2010. He was scrolling through news headlines on his iPhone when he spotted a headline about the FBI busting a Russian sleeper cell of 10 people long embedded as everyday U.S. citizens in various East Coast cities.

Amblin TV had just worked with Weisberg on an FX project dubbed “The Station,” about an overseas CIA station chief. From Italy, Frank emailed Falvey and Weisberg with the suggestion: “Wouldn’t this be a killer idea for a drama?”

Weisberg was intrigued. He immediately suggested setting the show in the 1980s, a time when the Cold War was at a fever pitch and fears of nuclear annihilation were high enough to inspire a landmark TV movie, 1983’s “The Day After” (which became an episode of “Americans,” Season 4).

When it came time to cast the show, Russell was attached early. Landgraf plucked her name off a long list of actresses under consideration for Elizabeth. “John just looked [the list] up and down and said, ‘Keri Russell — she can do this,’” Weisberg recalls. For Philip, Weisberg and pilot director Gavin O’Connor were sent in early 2012 to see Rhys in an Off-Broadway production of “Look Back in Anger.” “You could see some sides of Philip in that role,” Weisberg recalls.

But it was Russell who made the final call on her partner. During Rhys’ audition, the scene they read together called for her to deliver a hard slap. The actress, at O’Connor’s suggestion, didn’t hold back, smacking Rhys hard enough to leave a red mark on his cheek. He didn’t flinch. “It was incredible — they were just staring at each other. In that moment you could see the whole series,” Weisberg says.

Says Schrier: “As we joke with Matthew, that slap changed his life forever.”

Holly Taylor, who plays the Jenningses’ teenage daughter, Paige, came to the project through a videotaped audition reel. At age 14, she was already an alum of Broadway’s “Billy Elliot.” Keidrich Sellati was 10 when he signed on for the role of younger brother Henry.

Paige was destined from the start to be a pivotal character in the show — the older child who was first to question her parents’ activities. Weisberg knew from his own cloak-and-dagger days that lying to family members about the job is part of the description. But they had no idea how important Paige would be to the later seasons until they realized the depth of Holly’s talent.

“She could do so much,” Weisberg says. “If you’d told me back at the beginning that in some ways the whole show would revolve around that pole of the Jenningses’ life, I would have been very surprised.”

The pilot was produced in spring 2012 under the direction of Weisberg, showrunner Graham Yost (an FX veteran) and director O’Connor. Fields came into the picture after the pilot was ordered to series.

Weisberg had spent a season as a writer on the TNT drama “Falling Skies,” but he was in no way equipped to run his own television show. Fields had worked with FX on the dramas “Over There” and “Dirt.” He’d also developed a pilot script for TNT with Amblin TV. Fox 21 Television Studios president Bert Salke, a former drama showrunner himself, says Weisberg and Fields’ model for working together is unique. “[They] have an understanding of what they’re trying to do and how to do it through the most efficient and effective system I’ve ever seen in television,” he says.

In a nutshell, it’s all about preparedness. After filming ended each season, the writers would keep working for a few weeks outlining a half-dozen or more episodes of the next season, all in an effort to get a jump on the writing process for the following year.

Gavin Bond for Variety

The early flow of completed scripts had ripple effects across all departments. It allowed directors, costume designers, props, stunts, production designers and hair and makeup artists weeks rather than days to prepare for the needs of each installment. On a period drama, this extra time made all the difference. It also afforded the writers room plenty of time for what the showrunners see as a crucial element for quality control.

“We have our scripts written so far in advance that we end up having a lot of time to rewrite and rewrite and rewrite and rewrite. It is hard to describe how much better the scripts get because of having all that time,” Weisberg says. “Imagine if production only got those first drafts compared to what they’re actually shooting, which is often the fifth or sixth or seventh draft. It’s a completely different show because of all that rewriting.”

Though Weisberg and Fields were simpatico, it took time for them to find their footing on “The Americans.” At the outset, the show was more procedural in nature, with Philip and Elizabeth tackling a “case of the week.” They realized after the first season that the format was constraining, “because the spy stuff took up so much space,” Weisberg says. After much consultation with FX, “Americans” shifted gears to a more serialized approach to storytelling.

But the show defied convention from the start by positioning Russell’s character as its true antihero: Elizabeth is the tougher, colder and more ruthless member of the Jennings clan. Rhys’ Philip has always been the softer of the two, the one who allowed himself to be seduced by America and to find himself more in love with Elizabeth than she was with him.

The role at once required restraint, sensitivity and physicality for all the times Elizabeth fought her way into or out of a sticky situation. Russell sees “Americans” as a breakthrough for her as an actress. It also changed the course of her life off-camera: Russell and Rhys became romantically involved during the course of the series and welcomed the birth of their son, Sam, in 2016. “It was a real adult creative job for me,” Russell says. “I wasn’t playing a kid anymore. It kind of woke me up creatively.

“Elizabeth is tough and cool and strong and sexy and all of these things I really enjoy playing. You don’t always enjoy the characters you get to play.”

“Americans” over the years has also taken risks by serving up lengthy sequences in Russian with subtitles and investing in the Russian characters. Producer-director Long even took a small crew and co-star Costa Ronin, the good-hearted KGB agent Oleg Burov, to Moscow last year for a three-day guerrilla shoot. Going down that road was a subject of much discussion between Weisberg and Fields and the network, but in the end, all agree it was the right call.

“We’re not dumb,” Landgraf says. “If you’re going to have Russian themes, people speaking at length in subtitles, it’s not necessarily the obvious commercial decision. But as you watch the show unfold and see this final season, you’ll know it would not have been as good if that decision hadn’t been made.”

The show is enriched by its deft use of the period prism to examine heady themes of loyalty, patriotism and political ideology. It’s become famous for the many disguises that Philip and Elizabeth don for their trade. But at its core, “Americans” turns not on the capers or costumes but on the hard reality of maintaining a marriage, as seen from the perspective of the unusual union of two KGB agents who barely know each other’s real stories after years of living together.

A pivotal exchange between Costa Ronin’s Oleg and Matthew Rhys’ Philip was the subject of much fine-tuning during an editing session.

“To the extent the show is about the other themes — trust, identity and relationships between nation-states, politics as an expression of our morality — all of that is an extension of the marriage story,” says Fields. “The marriage serves as allegory for the nation-states, and the nation-states serve as allegory for the marriage.”

The Js have had an inkling of the broad arc of the series’ final storyline for some time. But they reserve the right to rewrite and rewrite and rewrite “until the last frame is locked,” Fields says. The pair wrote the final episode, titled “START,” which was directed by Long.

The details are, of course, highly classified. Cast and crew members have been trained over the years to zip their lips about spoilers. And Weisberg and Fields weren’t dropping any hints, not even to those near the top of the call sheet.

“I stopped trying to guess,” Taylor says. “My guesses were always so wrong. I always end up being so impressed with how the Js create these huge storylines and plot twists.”

Russell and Rhys say they’re extremely satisfied with the end of their 75-episode run as Philip and Elizabeth. Rhys joked that he was gearing up for a “big gun battle where somebody dies” — but nobody really expected Weisberg and Fields to take the easy way out.

“[The ending] they’ve created is so satisfying in a really surprising way,” Russell says. “It’s exactly in line with the tone of the show. It really got me.”

Landgraf promises that the last chapter of “Americans” is by turns heady and heart-wrenching in a way that fits the political moment. “The sixth season is a masterpiece in its interweaving of historical and interpersonal stories,” he says. “It looks at the downsides of nationalism and blind loyalty and the importance of real patriotism.”

After six years in the trenches, the loyalty between Weisberg and Fields remains fierce. The two plan to continue as producing partners, and they’re sticking with FX through an overall deal with FX Prods. “We’re staying at home,” Weisberg says. It’s a notable decision given the hotter-than-ever market for top showrunners thanks to Netflix’s eye-popping spending spree on superstar talent such as Ryan Murphy and Shonda Rhimes.

Fields has considered getting involved as a producer on new projects in addition to “Americans” during the past few years, but he always decided against it when Weisberg opted not to join him. “You make choices in a marriage,” Fields deadpans.

The pair in recent months have been discussing other program prospects. But they’re not looking too far into the future — not at the expense of the end of an era.

“We’re talking about some new ideas, but in our overly discussed, overly cerebrated way, we’ve made a conscious effort to stay focused on the end of ‘The Americans,’” Fields says. “We want to be able to look back on it and know that we gave it everything we had.”