This document is the first report in a two-part series that explores U.S. media coverage of the COVID-19 outbreak during the first 100 days of 2020. This first report examines the shape and flow of coronavirus coverage across time and digital spaces by using a large sample of stories from a range of news sources. Included in the report are interactive data visualizations showing the results of a computational analysis of 125,696 news articles from 66 widely-read national, metropolitan, and digital-only news websites. Findings indicate the U.S. coronavirus news story gained momentum in three distinct waves of coverage that culminated in a news tsunami in mid-March that spread through every news section from business and politics to health and sports. Certain stories were amplified and re-circulated across news sites and on social media, thus creating a network of diverse contributors to this vast news ecosystem. [For "The Shape of the Coronavirus News Story: Learning Resources. COVID-19: The First 100 Days of U.S. News Coverage," see ED613510. For the second report in this series, "Visual Messaging of the Coronavirus News Story. COVID-19: The First 100 Days of U.S. News Coverage," see ED613518.]