The ethnic composition of US inventors is undergoing a significant transformation — with deep impacts for the overall agglomeration of US innovation. This study applies an ethnic-name database to individual US patent records to explore these trends with greater detail. The contributions of Chinese and Indian scientists and engineers to US technology formation increase dramatically in the 1990s. At the same time, these ethnic inventors became more spatially concentrated across US cities. The combination of these two factors helps stop and reverse long-term declines in overall inventor agglomeration evident in the 1970s and 1980s. The heightened ethnic agglomeration is particularly evident in industry patents for high-tech sectors, and similar trends are not found in institutions constrained from agglomerating (e.g., universities, government).