I report new evidence for localized knowledge spillovers identified by within-patent variations in the geographic matching rates of citations added by inventors and citations added by examiners. Evaluated at the mean citation lag, inventor citations are 20% more likely than examiner citations to match the country of origin of their citing patent, whereas U.S. inventor citations are 25% more likely to match the state or metropolitan area of their citing patent. The localization of intranational knowledge spillovers declines with the passage of time, but international borders present a persistent barrier to spillovers.

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