The Proceedings of the 2021 US Community Study on the Future of Particle Physics (Snowmass 2021) is now available at https://www.slac.stanford.edu/econf/C210711/ .
Snowmass is a series of meetings that take place every few years, during which the US particle physics community discusses the future of the field with regards to the science, technology, infrastructure, and people. The conclusions of these discussions serve as community input for the strategic plan of US high energy physics research. See Chris Quigg’s paper How to Snowmass for more information about the philosophy of the Snowmass meetings.
INSPIRE gives access to historical Snowmass meetings on the planning of the future of particle physics in the US. To find past proceedings, go to INSPIRE conferences and search for series.name:”SNOWMASS”.