The AI Index, an independent initiative at Stanford's Human-Centered Artificial Intelligence Institute (HAI), tracks, collates, and visualizes data relating to artificial intelligence. Its mission is to provide unbiased, rigorous, and comprehensive data for policymakers, researchers, journalists, executives, and the general public to develop a deeper understanding of the complex field of AI. The 2019 edition tracks three times as many data sets as the 2018 edition and introduces two tools to help navigate the data: The Global AI Vibrancy Tool and arXiv Monitor.