The Mid-scale Research Infrastructure (MSRI) initiative is a National Science Foundation (NSF)-wide Big Idea designed to address the research community's growing needs for visionary and unique research infrastructure for the advancement of contemporary science and engineering research. NSF's MSRI program is designed to support the implementation of research capabilities and infrastructure with total project costs between $6M and $70M. In FY 2019, the NSF released two associated solicitations: Mid-scale RI-1 (NSF 19-537) for design and implementation projects requesting up to $20 million and Mid-scale RI-2 (NSF 19-542) for implementation projects between $20 million and $70 million. MSRI projects directly enable advances in fundamental science, technology, engineering, and mathematics (STEM) in one or more of the research and education domains supported by the NSF. The MSRI Program emphasizes strong scientific merit and response to identified needs of the research community, technical and managerial readiness for implementation, and a well-developed plan for student training and involvement of a diverse workforce in mid-scale facility development, and/or associated data management.