  Urban outputs, from economy to innovation, are known to grow as a power of a
city's population. But, since large cities tend to be central in transportation
and communication networks, the effects attributed to city size may be
confounded with those of intercity connectivity. Here, we map intercity
networks for the world's two largest economies (the United States and China) to
explore whether a city's position in the networks of communication, human
mobility, and scientific collaboration explains variance in a city's patenting
activity that is unaccounted for by its population. We find evidence that
models incorporating intercity connectivity outperform population-based models
and exhibit stronger predictive power for patenting activity, particularly for
technologies of more recent vintage (which we expect to be more complex or
sophisticated). The effects of intercity connectivity are more robust in China,
even after controlling for population, GDP, and education, but not in the
United States once adjusted for GDP and education. This divergence suggests
distinct urban network dynamics driving innovation in these regions. In China,
models with social media and mobility networks explain more heterogeneity in
the scaling of innovation, whereas in the United States, scientific
collaboration plays a more significant role. These findings support the
significance of a city's position within the intercity network in shaping its
success in innovative activities.
