International Geography

The domestic concentration documented in Domestic Geography is paralleled by a transformation in the international origins of US patent filings. Successive waves of foreign filings from Japan, South Korea, and more recently China have reshaped the composition of the US patent system, while the relationship between patent volume and quality varies substantially across countries.

This chapter examines the international dimension of innovation geography through three lenses: how domestic and international patents may differ in quality indicators, how patent quality and quantity relate across countries, and how country-level filing trends reveal the evolving composition of foreign patent activity in the US system.

US-domestic patents (where all listed inventors reside in the United States) and international patents (with at least one non-US inventor) differ systematically in quality indicators, reflecting differences in institutional contexts, research traditions, and strategic filing behavior.

The relationship between patent quantity and quality across countries warrants examination. Comparing average patent claims — a rough proxy for patent scope — across countries indicates that volume and quality do not necessarily correspond. Meanwhile, country-level filing trends over time reveal the evolving composition of foreign patent activity in the US system.

Beyond the snapshot comparison above, tracking quality metrics over time for the top patent-filing countries reveals how national innovation systems have evolved. The following charts compare the top five countries across four key quality indicators, showing long-run trends in citation impact, patent scope, research originality, and examination timelines.

Beyond quality metrics, the volume and trajectory of patent filings from different countries reveal the shifting composition of foreign inventive activity within the US patent system. Japan, long the dominant foreign filer, has been joined by South Korea and China as major sources of patent applications, while European countries have maintained steady but less rapidly growing filing volumes.

The priority country of a patent reveals where the invention was first filed, providing a complementary lens to inventor location. Tracking priority country composition over time illuminates the shifting national origins of inventions entering the US patent system, including the rapid rise of East Asian filing activity.

The Patent Cooperation Treaty (PCT) route provides a standardized international filing pathway. The share of a country's US patent filings that enter via the PCT route reveals differences in filing strategies across national innovation systems. Higher PCT usage generally indicates greater reliance on international filing pathways.

Extending the geographic lens beyond national aggregates, innovation clusters worldwide exhibit similarly pronounced concentration patterns. The following analysis ranks global cities by their total patent output in the US patent system, revealing which metropolitan areas function as the primary engines of patented invention worldwide.

The international filing patterns and quality metrics documented in this chapter complete the geographic analysis of the US patent system. Having examined where innovation happens — from state-level domestic concentration to global filing patterns and cross-country quality comparisons — the narrative turns to how knowledge flows through the system. The next act, The Mechanics, investigates the organizational, individual, and geographic channels through which knowledge circulates, beginning with Organizational Mechanics and the within-firm dynamics of exploration, exploitation, and inter-firm knowledge flows.