Overview
- The precision‑milled stainless‑steel cylinder was filled and sealed at NIST and is scheduled to be interred beneath a new sculpture on Independence Mall on July 4, 2026, with instructions to stay closed until July 4, 2276.
- Engineers designed the roughly 900‑pound vessel as a smooth cylinder to reduce seepage, used compressed indium for an airtight, watertight seal, targeted about 35 percent interior humidity, and will cover the capsule with a half‑ton bell jar to protect it underground.
- The capsule holds hundreds of items submitted by states, territories and federal partners, ranging from poems and governors’ letters to a fusion superconductor, a whale bone, Native artwork and a tiny Library of Congress vial of synthetic DNA encoding digitized documents.
- Federal agencies including America250, the Library of Congress, NIST and the National Park Service coordinated the project, but experts warn long‑term risks such as water ingress, climate change and the challenge of keeping institutional custody over 250 years.
- Congress directed the effort in 2016 as part of the semiquincentennial; the project not only preserves artifacts but also raises questions about what choices in curation and technology will mean for the people who open the capsule in 2276.