China has overtaken the United States in total number of AI research citations, fewer AI startups are receiving funding, and Congress is talking about AI more than ever. Those are three major trends highlighted in the 2021 AI Index, an annual report released today by Stanford University. Now in its fourth year, the AI Index attempts to document advances in artificial intelligence, as well as the technology's impact on education, startups, and government policy. The report details progress in the performance of major subdomains of AI, like deep learning, image recognition, and object detection, as well as in areas like protein folding. The AI Index is compiled by the Stanford Institute for Human-Centered Artificial Intelligence and an 11-member steering committee, with contributors from Harvard University, OECD, the Partnership on AI, and SRI International.