Snapchat daily active users

Between 2015 and 2022, Snapchat's daily active users grew from 107 million to 363 million, and New Yorkers took increasingly more trips on Citi Bikes, apparently in perfect lockstep. One could conclude that every disappearing photo sends a New Yorker hurtling toward a docking station, helmet optional. Perhaps the ephemerality of Snapchat content inspires a philosophy of impermanent transit — why own a bike when you can rent one for exactly as long as your selfie exists? The streets of Manhattan have never looked so algorithmically optimized.

Both Snapchat's user growth and Citi Bike ridership track the same demographic wave: millennials and Gen Z in urban environments adopting new platform behaviors during roughly the same half-decade window. Citi Bike expanded from around 10 million annual trips in 2015 to over 30 million by 2022, driven by infrastructure investment, app-based docking integration, and urbanist shifts toward micro-mobility. These are parallel adoption curves within overlapping user populations rather than causally linked phenomena. Both also benefited from sustained investment cycles and network effects that make the growth curves look similar in shape.

Parallel adoption curves within the same demographic cohort are among the most seductive traps in correlation analysis — they look like causation because they share a common cause in the same humans making similar lifestyle choices simultaneously. The ghost in this data is a 28-year-old with an unlimited MetroCard and a phone in their hand, counted twice.