In some ways, the hottest show of early 2018 is a series that debuted in 1994.

Ever since all 331 episodes of ER, the landmark hospital drama that aired on NBC for 15 seasons between 1994 and 2009, landed on Hulu in January, my social media feeds have been filled with TV critics, TV fans, and random people who are now remembering why the show became one of the biggest hits of all time.

This is what happens when I don't follow my advice and just start rewatching the whole damn thing: https://t.co/b8l5Y7hzSk — Alan Sepinwall (@sepinwall) February 6, 2018

The early seasons of ER on Hulu helped me through an extremely rough patch a couple weeks ago. Old TV is therapeutic as hell https://t.co/15wN6ZA7Xd — Oriana Schwindt (@Schwindter) February 9, 2018

Just rewatching ER on Hulu and remembering how extremely great Eriq La Salle is. This part just happened and it was thrilling. pic.twitter.com/VcXkZyNcJd — Heather & Jessica (@fuggirls) January 17, 2018

Watching the first episode of ER on @hulu...You really wouldn't know this show is 25 years old. Timeless. — Julia O'Donoghue (@JSODonoghue) February 3, 2018

HOW DID NO ONE TELL ME ER IS ON HULU THANK YOU UNIVERSE I NEEDED THIS THANK YOU — Katie Bo Williams (@KatieBoWill) February 3, 2018

ER, with its lightning-quick storytelling and propulsive filmmaking, is a perfect fit for the “just one more episode” streaming television era. It simply took a really long time for the show to find a streaming home, in a similar fashion to how other shows from Warner Brothers Television (the studio that produced ER), like Friends and Gilmore Girls, didn’t immediately make their way to Netflix.

But now that it’s available in its entirety, viewers are flocking to ER and shoving aside other, newer TV shows in favor of its mid-’90s charms. And what’s even more remarkable is that the show doesn’t feel particularly dated, in the way other series of its ilk often do. Sure, the fashion and hairstyles are out of date, and what social issues it touches on (from HIV to medical privacy) are rooted in the era it was made in. But overall, it feels like it could be dropped onto the air right now and still be compulsively watchable.

That’s quite a shift for a series that probably spent too many seasons on the air and eventually got a little too amped-up and silly. But the TV climate of 2018 is uniquely susceptible to a show like ER, for a bunch of reasons.

Let’s start with Hulu itself.

ER presented some major risks for any service that considered bringing it into the streaming era

Consider for a moment that streaming deals for old shows are based on the number of episodes in a show’s run. Now consider that as more and more TV libraries (any entity that controls the post-air rights to any TV show — usually a studio, but not always) realize the value that older shows in their back catalogs present to streaming services, they’re less likely to sell those shows in package deals and more likely to make blockbuster deals around individual series (especially series that were big hits when they were on the air). Given that ER was extremely popular and ran, all told, for 331 episodes (and technically 333 episodes, thanks to its double-length pilot and finale), you can imagine where closing a streaming deal for the season might have taken some fancy negotiating.

Lisa Holme, Hulu’s vice president of content acquisitions, says she initially wasn’t convinced that ER was a must-have for the service. “To be totally transparent, it was not a no-brainer, because we thought there were some potential risks in terms of if it would really work in this streaming environment,” she says.

Those risks extend beyond the financial. Just the sheer volume of stuff viewers have available to them in 2018 means that trying to get them to watch a show with over 300 episodes is always going to be a tall order. And that’s especially true for a show like ER, which is serialized enough that I’d recommend watching the show straight through from the beginning, as opposed to picking and choosing favorite episodes like one might do with a more close-ended procedural like Law & Order. Holme and her department worried that the sheer number of ER episodes would cause viewers to avoid it by in favor of something more manageable.

But the series’ viewership has surpassed Hulu’s expectations, and Holme says it’s been gratifying to watch a cluster of viewers slowly make their way from season to season. The service does not release hard viewership numbers, but reports that Hulu subscribers who’ve watched ER in its first month since it launched in January 2018 have consumed, on average, 19.4 hours of the show per viewer — a remarkable number when you consider that it factors in lots of people who’ve only watched a couple episodes. What’s more, around 5,000 Hulu subscribers finished the entire series in its first month on the service — which works out to around eight hours of ER per day.

But even if ER had been a bust, acquiring it might have been worthwhile just to help solidify in the minds of TV fans that Hulu is dedicated to building a repository of the best TV ever made, in addition to creating original series of its own. Holme says the service keeps tabs on when shows that are routinely listed among the best ever (as ER has been for years) become available, and as other streaming services shed older shows from their libraries, Hulu scoops them up (as I wrote about here).

“We really do try to think about having, for whatever mood you’re in at the moment, whether that’s the very high-end, high-intensity viewing, or the kind of lean-back comfort food, we want to make sure we have something for you,” Holme says.

So, okay, that’s how ER ended up on Hulu. But why has it seemed so fresh and engaging to the viewers of 2018? To answer that, we have to go all the way back to the show’s mid-’90s debut.

ER broke new ground for TV visuals and direction, while honing the dominant dramatic storytelling style of its era to a fine point

The first thing you might notice about ER (which was created by novelist Michael Crichton and turned into the TV obsession it became by veteran writer John Wells) is how frantic it is. As critic David Sims of the Atlantic (the foremost ER expert I know and a former colleague of mine from The A.V. Club) put it to me, the door to the hospital can open and the entire course of an episode can shift at essentially any moment. The series’ camerawork is complicated and choreographed, moving in and around the operating theater, up and over patients, into spaces that doctors used to occupy. If you stop to think about it, you might realize how little logical sense it makes, but it captures the emotion of a tense hospital, where life and death stakes are the norm.

“It just suddenly felt like you were in a place rather than watching a TV show,” Sims says.

It was this quality that helped ER win a major ratings war in 1994, when it debuted on NBC in the exact same timeslot as the equally hyped Chicago Hope on CBS. Chicago Hope was a more traditional, staid hospital drama from the prolific creator David E. Kelley; it garnered more initial hype and slightly kinder early reviews, and it went on to a respectable six-season run. But it felt very akin to the TV dramas of the 1980s — talky and earnest and engaged with the issues of the day, but not exactly high-octane.

It was, in other words, nothing compared to ER, which could randomly morph into an action movie at any given moment. (Sims credits the series with completely rewriting how action scenes worked on TV. Compare a heart-pounding surgery on ER to a fight scene on The A Team and see which looks more like modern-day action shows.) Where other hospital shows gave you talk, ER would give you action, and the list of directors who worked on it (especially in its early seasons) reads like a who’s who of TV directors from the last 25 years — particularly Mimi Leder, who went on to make feature films and head up the direction of HBO’s The Leftovers after ER, and Thomas Schlamme, who in his later work with Aaron Sorkin applied ER-style Steadicam shots to people spouting exposition to perfect and popularize the shot known as the “walk and talk.”

But where ER was a revelation in terms of TV filmmaking, its storytelling fell solidly within the tradition of TV dramas to that point, which is to say that it was a workplace drama in the vein of Hill Street Blues, the legendary 1980s cop show that pioneered the blend of workplace storylines, social issues examinations, and personal character arcs that ER would hone to a fine point. Both shows featured cases of the week, and sometimes those cases touched on the social issues of the day. But the real reason anyone kept watching ER or Hill Street Blues or, say, LA Law is that you could see the characters grow and change — if slowly.

And the original ensemble cast of ER was full of great characters whose lives were worth following. Today, the series is probably best known for giving George Clooney and Julianna Margulies their big breaks, but every actor is formidable, and the best thing about re-watching it is being reminded of how tremendous actors like Eriq La Salle and Gloria Reuben were in their roles and how much their characters grew and changed over time.

“I think because the [medical cases are] fast-paced, you maybe don’t notice how much character development is happening over the course of a season, or over the course of a major arc,” says Margaret Lyons, a TV critic for the New York Times, who says she hung pictures of ER’s characters in her middle-school locker.

This sense of deep character development, of everybody in the show’s universe both having a job and really caring about both that job and their professional advancement is often why ER plays so well when viewed through 2018 eyes. That devotion to making sure everybody within the series has their own point-of-view, says Uproxx critic Alan Sepinwall (who recently wrote about falling back into the show), is reminiscent of some of the more complex cable dramas that debuted in the 2000s, like The Wire.

“It’s not just the characters themselves. It’s the whole hospital feels alive in a way that not a lot of other shows do,” Sepinwall says.

What was routine about ER in 1994 feels surprising and revolutionary in 2018

In every conversation I have about ER, it’s inevitable that Grey’s Anatomy, the hospital drama that took ER’s place as TV’s biggest medical show, will come up at some point. What’s fascinating about comparing the two shows is that Grey’s Anatomy’s focus on personal relationships and soapy complications, the thing that set it apart from ER when it debuted in 2005, and still makes it compelling today, 14 seasons later, is now the thing that feels a little more predictable and tired, thus making ER feel as newly vital as it does.

This is how TV works. The longer a series remains on the air, the more we get used to its rhythms and the harder it is for the series to surprise us. ER, deep in its run, came to over-rely on its kinetic rush and action movie approach; eventually things got so over-the-top that one character was killed when a helicopter fell on him. But where Grey’s felt so fresh precisely at the moment when ER had grown old enough for viewers to have become inured to its rhythms, ER now feels like an antidote to roughly 20 years of TV trends that sprung up as a response to the sorts of TV storytelling it came to represent.

“ER is weirdly low-concept,” Lyons says. “It’s a hospital show. Is it an amazing hospital? Not really. Is everybody super in love? No. Is somebody a superhero? No.”

The show is about its workplace in a way that feels almost daring in 2018, where it would be much more tempting to come up with a high-concept pitch or, at least, one very important, central character (as with ABC’s first-season hit The Good Doctor or the Fox show House, which ran from 2004 to 2012). ER always keeps a steady, watchful eye on its patients, but its focus remains on the people who work in the hospital, the people who make it tick.

ER feels so weirdly fresh now because it’s the type of show that’s fallen a little out of favor in the antihero era that TV has been stuck in (or responding to) since the debut of The Sopranos in 1999: an ensemble drama. Indeed, when I ask Sims what modern shows could learn from ER, he points to this very aspect.

“You should have a lot of faith in your ensemble, rather than building a show around a lead character, or building a show around personality problems,” he says.

ER is packed with great characters, but more importantly, it’s packed with great dynamics between those characters. Some of them get along. Some of them don’t. Their relationships grow and change, and their professional goals grow and change, and the hospital stays the same. It’s easy to imagine, with a few tweaks of the imagination, that its doors are being thrown open right now, not back in 1994.

“It feels really natural and lived in. Even though you’re watching stuff from 20, 25 years ago practically, it feels oddly modern,” Sepinwall says.

Some of that can be attributed to the fact that a great TV show will remain a great TV show, and it might take a little time for us to see it with new eyes. But just as much, I think, stems from how few shows on the air right now can do what ER does well. If ER was being made today, it would probably be centered on a difficult but ingenious doctor and the colleagues forced to deal with his temper and his genius. It might be an okay show, and it might be one worth watching — but it would never be ER.

Correction: Margaret Lyons hung photos of the ER cast in her middle-school locker, not her high-school one. “I was a loser. But I learned how to hide it better, eventually,” Lyons reports via email. We regret the error.