Forthcoming
Article
Quarterly Journal of Economics

The Diffusion of New Technologies

By: Aakash Kalyani, Marcela Carvalho, Nicholas Bloom, Tarek Hassan, Josh Lerner and Ahmed Tahoun

Abstract

We identify phrases associated with novel technologies using textual analysis of patents, job postings, and earnings calls, enabling us to identify four stylized facts on the diffusion of jobs relating to new technologies. First, the development of economically impactful new technologies is geographically highly concentrated, more so even than overall patenting: 56% of the most economically impactful technologies come from just two U.S. locations, Silicon Valley and the Northeast Corridor. Second, as the technologies mature and the number of related jobs grows, hiring spreads geographically. But this process is very slow, taking around 50 years to disperse fully. Third, while initial hiring in new technologies is highly skill biased, over time the mean skill level in new positions declines, drawing in an increasing number of lower-skilled workers. Finally, the geographic spread of hiring is slowest for higher-skilled positions, with the locations where new technologies were pioneered remaining the focus for the technology’s high-skill jobs for decades.

Keywords

Technology; Geography; Innovation; R＆D; Technological Innovation; Research and Development; Employment; Geographic Location

Citation

Kalyani, Aakash, Marcela Carvalho, Nicholas Bloom, Tarek Hassan, Josh Lerner, and Ahmed Tahoun. "The Diffusion of New Technologies." Quarterly Journal of Economics (forthcoming). (Pre-published online January 17, 2025. Earlier version distributed as National Bureau of Economic Research Working Paper No. 28999 and Harvard Business School Working Paper No. 21-114. Related discussion published as “How Disruptive Technologies Diffuse,” VoxEU, 2021.)