GAITHERSBURG, Md., July 3, 2026—A time capsule will be buried at Independence National Historic Park in Philadelphia tomorrow as part of the 250th anniversary celebration of the signing of the Declaration of Independence.

It will contain items and records from all three branches of the federal government; all 50 states; Washington, D.C.; five U.S. territories and other organizations and agencies.

And it will be buried for 250 years, to be opened in the year 2226.

That’s two-and-a-half centuries underground.

To ensure the items inside are as fresh 250 years from now as the day they were inserted, Americe250, the organization charged by Congress to run the time capsule project, went to the National Institute of Standards and Technology to design the capsule.

The institute builds one-of-a-kind scientific instruments—intricate apparatuses of stainless steel and high-vacuum glass—researchers use to do things like manipulate individual atoms or detect the impact of a single photon of light on a sensor. It was charged with designing a capsule to ensure the items remain pristine when opened 250 years from now.

The time capsule consists of two main pieces—the time capsule itself and a larger bell jar that fits over the capsule. Both are precision-milled, stainless-steel cylinders with a combined weight of one ton.

Because the main threat to the capsule is water, the bell jar, once fitted over the capsule, will trap a pocket of air, much like an upside down bucket pushed into a swimming pool does. This will protect the contents from floods or a rising water table.

Each submitted item was documented and photographed before being inserted into the time capsule. The pieces are then stored in acid-free archival boxes and stacked on shelves within the capsule.

The capsule is sealed with a soft-metal indium compression wire that flattens when the lid is tightened. This ensures an airtight and watertight seal for a burial depth of at least 8 feet.

The time capsule will be buried close to the Liberty Bell at Independence National Historic Park during a dedication ceremony at 8:30 a.m. tomorrow.