You can get the information about Archives' open status under the influence of COVID-19 below.
9/7/2020 update
【United States of America】
・National Archives and Records Administration
・National Archives in Washington, DC
・National Archives at College Park, MD
https://www.archives.gov/coronavirus
A Message from the Archivist to Our Researchers(6/12/2020/)
https://www.archives.gov/news/message-from-archivist-to-researchers
・Library of Congress
https://www.loc.gov/about/pandemic-information/for-public/
・Gordon W. Prange Collection (University of Maryland)
https://www.lib.umd.edu/about/coronavirus-updates
https://www.lib.umd.edu/about/coronavirus-updates#phases (Reopening Plan)
*Libraries’ Tentative Phase 1 Plans for “Reopening,” targeted for July 13, 2020
https://www.lib.umd.edu/news/2020/06/libraries-phase-1-of-reopening-commencing-july-13
※University of Maryland Fall 2020 Reopening Plan
※University of Maryland COVID-19 Dashboard
https://umd.edu/covid-19-dashboard
※MaryLand Today
【United of Kingdom】
・The National Archives UK
https://www.nationalarchives.gov.uk/about/news/coronavirus-update/
【Australia】
・National Archives of Australia
https://www.naa.gov.au/covid-19-important-information-about-our-services
・Australian War Memorial
https://www.awm.gov.au/visit/visitor-information