“From This American Life and WBEZ Chicago, it’s Serial. One story told week by week. I’m Sarah Koenig.”

Though relatively harmless and not all that memorable, this line from 2014 reshaped entertainment media and thrust podcasts into the popular mainstream. It’s no “call me Ishmael”, but neither This American Life, Sarah Koenig, the rest of the Serial staff, nor hundreds of thousands of people who initially heard this line realized at the time the importance of what they were experiencing. Before Serial, only 27% of the US had listened to a podcast.

Podcasts became a thing. At least for the time being.

Podcasts existed and were popular with a segment of the population well before Serial launched, but now they were a thing in a more grandiose manner. For the first time, podcasts were part of the monoculture. There was even an SNL skit parodying Serial.

See the Serial spike in search volume in late 2014.

Serial was a true crime podcast analyzing the possible crime, but definite conviction, of Adnan Syed who was accused of killing his girlfriend in 2010. He was issued life in prison without the possibility of parole. Due to the ambiguity in the case, many unanswered questions, and apparently enough reasonable doubt the podcast producers deemed his story compelling enough to be made into a 12-episode podcast.

The monoculture Serial created hasn’t quite been replicated since. The second installment of Serial was popular, but not to the same extent. So was 2017’s hit from the same studio, S-Town. But still not quite the same. Instead, imitators emerged trying to resurrect Serial’s success. Though no podcast succeeded with this mission, the combined force of true crime podcasts came to define the podcast medium as a whole. True crime podcasts reign supreme. Look at the Apple Podcast charts on any given day and you’ll likely see a few inside the top 10.

Currently, Atlanta Monster is the true crime du jour. Before that it was Dirty John. Before that it was S-Town. Before that it was Up and Vanished. You also have the episodic true crime podcasts like CriminalMy Favorite Murder, and others constantly producing podcasts and compelling stories, subsequently keeping the true crime genre top of mind.

How did we get here though? Serial was supposed to propel all podcasts to the mainstream, not just true crime.

Though it’s tough to quantify how this happened, we have qualitative examples of how this happened with other mediums. The easiest proxy is to compare HBO’s The Jinx, and Netflix’s Making a Murderer — two true crime documentary series that in their respective moments entered the monoculture and became watercooler conversation.

For all their marketing firepower, HBO and Netflix have also become incredible engines propagating word of mouth recommendations. Think back to when you first viewed one of those series, chances are your interest was piqued with someone asking “Have you seen The Jinx yet?!” Despite being major names with literally millions of subscribers, both networks still rely on inter-personal recommendations that an algorithm can’t quite reproduce. For whatever reason, true crime lends itself the best to stoking word of mouth recommendations. Maybe it’s people’s desires to talk about their thoughts on the case. Or maybe it’s that weird unspoken social currency of knowing the ending before someone else. Either way, the true crime genre is somehow manufactured to encourage people to share it with others.

The last few years the general public has said “there’s too much tv” and on any given week there are new shows from HBO, Netflix, Amazon, Hulu, ABC, NBC, CBS, Fox, FX, Starz, Showtime, Bravo, Comedy Central and a couple other channels you’d like to try out. Actual dozens of new shows you’d like to watch.

Podcasts take this example to the extreme. By most estimates, we’re approaching 500,000 podcasts, and they’re still growing extremely fast. It’s impossible to keep up with all the new podcasts, and because there’s no real discovery mechanism to find new podcasts, word of mouth remains the main driver for new listeners.

While Serial was looked at as propping up podcasts as a whole, instead it became the first real example of how much a podcast’s success is dependent word of mouth recommendations. Though this is largely still the case, there are now more quality true crime examples to diversify the listener base and the fragmentation has quelled any more monoculture podcasts from entering the mainstream limelight.

Podcasts, at least for now, remain a true crime-dominant medium.