Adoption Curves of Major Technologies
The telephone took 71 years to reach 50% of US households. Electricity took 30. Television took 26. The internet did it in 15. Smartphones in 8. Generative AI tools reached 100 million users in two months. Each successive general-purpose technology has been adopted faster than the one before — though 'adoption' has come to mean increasingly different things.
Key insights
Infrastructure was the slow part
The telephone (1876) and electricity (1882) required physical infrastructure — wires to every household — that took decades to roll out. Cost was secondary; capacity wasn't there to build. Subsequent technologies inherited those wires (radio, TV piggybacked on broadcast; the internet used phone and cable lines initially) and accelerated past the infrastructure constraint.
Wireless changed the curves further
The mobile phone (1973 demonstration, 1983 commercial) and smartphone (2007) reached billions of users far faster than wired technologies because the infrastructure (cell towers) is cheaper per user than running wires to each home. The S-curves got steeper. The remaining wired-broadband infrastructure question is now mostly about quality and last-mile fibre, not basic connectivity.
What counts as 'adoption' has changed
ChatGPT reached 100 million users in two months — but those are weekly active users of a website, not the sort of 'household ownership' the telephone or TV figures track. Each new technology measures adoption against its own meaningful threshold. The trend toward faster diffusion is real, but the apples-to-apples comparison is harder than the headline numbers suggest.
Years from introduction to 50% US household adoption
Major consumer technologies
Key Finding: Adoption times have shrunk from decades to years to months over a century.
Adoption curves — selected technologies (US households)
% adoption, years from introduction
Key Finding: Each curve is an S-shape but the slopes have steepened dramatically across the 20th century.
Methodology & caveats
Defining the start date
Invention dates can be argued — the telephone was patented in 1876 but commercial service started in 1878; the internet's ARPANET began in 1969 but most adoption series start from 1991 (the public web). Adoption curves usually start when a technology becomes commercially available to consumers, not when first patented.
Adoption thresholds
Headline figures use 50% household adoption — but the US Census measures households, not people; not all members of a household use the technology equally; and households are not directly comparable to the modal user of mobile-era technologies. The 50% threshold is a convention, not a universal definition.
Recent technologies vs household-survey legacy
ChatGPT and similar AI tools are typically measured in active users of a service, not household ownership. This is a meaningful change in measurement, not just in pace. Generation-spanning S-curves probably look smoother than the underlying reality, especially for digital products with rapid feature changes.