The deadline for submission of letters of interest (LoIs) for the US Snowmass 2021 process was Monday, August 31. There were ~1600 LoIs submitted and all of them can be found here: https://snowmass21.org/loi .

I was personally involved in or led a few:

• Cosmic Neutrino Probes of Fundamental Physics [pdf]
• Neutrino cross-sections and interaction physics [pdf] (with Amy Connolly & Spencer Klein)
• New physics with astrophysical neutrino flavor [pdf] (with Carlos Argüelles, Teppei Katori, Ali Kheirandish, Sergio Palomares-Ruiz, Jordi Salvadó, Aaron Vincent)
• Ultra-High-Energy Neutrinos [pdf] (with Peter Denton & Stephanie Wissel)
• Target of Opportunity Observations with Next-Generation High-energy Neutrino Observatories [pdf] (with Claire Guépin & Tonia Venters)
• An Andean Deep-Valley Detector for High-Energy Tau Neutrinos [pdf] (with Carlos Argüelles & Andrés Romero-Wolf)
• GRAND: Giant Radio Array for Neutrino Detection [pdf]

Here is a plot I prepared, with feedback from many others, for Cosmic Probes of Fundamental Physics: