How it happened
New York's tech industry grew steadily through the 2010s, partly by proximity to finance (fintech), media (ad tech and media tech), and fashion (e-commerce), and partly because the city's concentration of talent and institutions makes it attractive for companies that need people across many disciplines. Cornell Tech's campus on Roosevelt Island, which opened in 2017, was a deliberate attempt to anchor an academic tech hub in the city — and has had a measurable effect on the ecosystem around it.
Where it actually lives
Flatiron / Silicon Alley — the original nickname for New York's tech cluster, centred around the Flatiron Building on 23rd Street. Still the densest concentration of tech office space in the city, though the companies have spread significantly beyond it.
DUMBO and Brooklyn — tech companies and startups have moved heavily into DUMBO's converted industrial buildings, and the Brooklyn tech scene has become substantial enough to be self-sustaining rather than just Manhattan overflow.
Long Island City — Amazon's aborted HQ2 project was planned here; when it fell through in 2019, the area continued developing anyway as tech and office tenants moved in regardless.
What it means for visitors
The tech industry's concentration in specific neighbourhoods has contributed to the rapid change in Williamsburg, DUMBO, and Long Island City visible over the last decade — rising rents, new restaurants and cafés calibrated to tech salaries, and the displacement of earlier residents and businesses that comes with that.