The EarthScope project was an National Science Foundation (NSF) funded earth science program that, from 2003-2018, used geological and geophysical techniques to explore the structure and evolution of the North American continent and to understand the processes controlling earthquakes and volcanoes. The project had three components: USArray, the Plate Boundary Observatory, and the San Andreas Fault Observatory at Depth. Organizations associated with the project included UNAVCO, the Incorporated Research Institutions for Seismology (IRIS), Stanford University, the United States Geological Survey (USGS) and National Aeronautics and Space Administration (NASA). Several international organizations also contributed to the initiative. EarthScope data are publicly accessible. Observatories There were three EarthScope observatories: the San Andreas Fault Observatory at Depth (SAFOD), the Plate Boundary Observatory (PBO), and the Seismic and Magnetotelluric Observatory (USArray). These observatories consist of boreholes into an active fault zone, global positioning system (GPS) receivers, tiltmeters, long-baseline laser strainmeters, borehole strainmeters, permanent and portable seismographs, and magnetotelluric stations. The various EarthScope components will provide integrated and highly accessible data on geochronology and thermochronology, petrology and geochemistry, structure and tectonics, surficial processes and geomorphology, geodynamic modeling, rock physics, and hydrogeology. Seismic and Magnetotelluric Observatory (USArray) USArray, managed by IRIS, is a 15-year program to place a dense network of permanent and portable seismographs across the continental United States. These seismographs record the seismic waves released by earthquakes that occur around the world. Seismic waves are indicators of energy disbursement within the earth. By analyzing the records of earthquakes obtained from this dense grid of seismometers, scientists can learn about Earth structure and dynamics and the physical processes controlling earthquakes and volcanoes. The goal of USArray is primarily to gain a better understanding of the structure and evolution of the continental crust, lithosphere, and mantle underneath North America. The USArray is composed of four facilities: a Transportable Array, a Flexible Array, a Reference Network, and a Magnetotelluric Facility. The Transportable Array is composed of 400 seismometers that are being deployed in a rolling grid across the United States over a period of 10 years. The stations are placed 70 km apart, and can map the upper 70 km of the Earth. After approximately two years, stations are moved east to the next site on the grid – unless adopted by an organization and made a permanent installation. Once the sweep across the United States is completed, over 2000 locations will have been occupied. The Array