The Girl on the Train switch from Londra to New York explained 

Perhaps the biggest — and most jarring — surprise for the millions of readers of Paula Hawkins’s 2015 novel

is that the film is no longer set in the book’s London and its outskirts. Instead, Emily Blunt’s Rachel Watson rides New York’s Metro-North commuter rail from Westchester County to Manhattan every day, heading to Grand Central Station, not London Euston as in the novel. But there’s a consolation: Blunt herself remains British, which director Tate Taylor (

) thought would be “a fun wink and nod to the novel,” and could also highlight how isolated and untethered Rachel is, an ocean away from family and most friends.

), leaving the movie in London “wasn’t even on the table” when she started her adaptation. DreamWorks bought the book’s film rights in the spring of 2014, and Wilson turned in her first draft of the script the same week the novel was released in the U.S., in January 2015. “The book had not come out [when I was working on the screenplay],” Wilson tells EW. “I’ve been down this road enough that sometimes the book isn’t even noticed… Just because it’s really good doesn’t mean [the book] will do well,” she says. “This is an American film, and that was it.” Keeping it in America seemed like a no-brainer.

While Wilson considered other U.S. settings, like Seattle or the South, she landed on the Hudson River Valley partly because of her filmic inspirations – like 2002’s

– but also because of her own experience taking the Metro-North Hudson line from New York to Poughkeepsie. “The train itself is totally unsexy,” she says. “But the river is, and the backyards, and the suburbs – Croton-on-Hudson and Dobbs Ferry, all these places you look at when you’re coming out of the grayness of the city and you think, ‘Oh my God, I could live there.’ There’s a lot of dreams there.”

Initially, she had Emily Blunt’s protagonist Rachel Watson living in Poughkeepsie after having lost both her husband and her job, and losing herself even further to alcoholism. Wilson loved the way the train would carry Rachel from her former routine – a job in the city and a house in the beautiful suburbs – and then take her past those stately houses into the drabness of Poughkeepsie. “She passes her old life, her dream life, and she goes to her rented, borrowed room,” Wilson says. “Her sh–ty apartment in Poughkeepsie.” In the finished film, Rachel doesn’t end up living in Poughkeepsie – but she’s farther north than Ardsley-on-Hudson, where she lived with her ex-husband, Tom (Justin Theroux), and where he still lives with his new wife, Anna (Rebecca Ferguson).

The American setting, Wilson says, also brought an extra veil of shame to Rachel’s alcoholism. “It’s much more of a drinking culture [in England],” Wilson says. “It’s not as shameful as it is here.” American bars are dark, she says: “In America, [drinking at bars] is all about going into a dark hole where nobody can see you do a bad thing.” You wouldn’t necessarily sit there with a cocktail on the Metro-North train – which is why Rachel chooses to keep her vodka in an unassuming water bottle – but on the English trains, Wilson says, an evening drink may be more acceptable.

None of these changes in the film alter the pitch-black tone of the novel – in fact, even author Paula Hawkins was fine with the shift. “I never thought the location was the most important thing,” Hawkins says. “I think one of the reasons [the novel has] done well is that voyeuristic impulse, that urge to look at others, is a universal thing. I always thought that story would translate to any kind of city where people commute, whether it’s by train or by subway or what have you.”

Hawkins adds, “I do think where they’ve set it, that part of upstate New York, lends something extra to it because it is beautiful, but it’s beautiful in a slightly creepy way.”

But there’s one detail from the novel that will be sorely missed by readers: Rachel’s ubiquitous canned gin and tonics, her beverage of choice for those long train rides. “The canned gin and tonic is so sad and so creepy, right?” Wilson laughs. “It’s so pathetic, and I love that about it. And I love the humor in that, but I couldn’t do it.” At least both versions of the story still include wine.

, pick up the new issue of Entertainment Weekly, on stands Friday, or buy it now. Check back to EW.com for even more

scoop – and don’t forget to subscribe for more exclusive interviews and photos, only in EW.

Daisy Ridley says next \'Star Wars\' title won\'t be revealed for a while

Emily Blunt shares Julie Andrews\' reaction to her Mary Poppins casting

Kevin Smith recalls awkward text exchange with daughter

‘The Goldbergs’ enlists ‘The Office’ alum for ‘Brady Bunch’ episode

Britney Spears says Carpool Karaoke was \'fun,\' \'awkward\'

See the Voices Behind Your Favorite \'Kim Possible\' Characters