Trade substitution and similarity to Chinese patent text: evidence from USPTO patents

China’s innovative capacity has expanded rapidly. I examine whether trade substitution towards China strengthens its influence on subsequent innovation abroad. To study this possibility, I exploit the 2011 Tōhoku earthquake, which abruptly disrupted pre-existing supply relationships with Japan. I use patent-text similarity to capture one dimension of this influence. Specifically, I compare abstracts from 1.43 million foreign USPTO patent applications filed during 2008–2020 with prior-year Chinese patent abstracts in the same IPC subclass. Following the earthquake, foreign patent abstracts in technology fields with greater predetermined exposure to Japan became significantly more similar to recent Chinese patent text. This result is robust to alternative exposure measures, timing definitions, trend controls, patent-quality adjustments, and inventor-location restrictions. Complementary product-level trade estimates show that greater pre-earthquake dependence on Japan predicts lower imports from Japan and higher imports from China, consistent with partial substitution towards China. Taken together, the findings suggest that supply-chain adjustment may be one channel through which Chinese innovation affects subsequent innovation abroad. Trade and innovation policy should therefore not be treated as entirely separate domains.