To celebrate the 250th anniversary of the United States' founding, a 408‑kilogram time capsule has been assembled, containing items representing contemporary America, and is planned to be buried in Philadelphia on July 4.
Four African American students staged a nonviolent protest after being denied service at a Woolworth's store in Greensboro, an event considered to have helped push for the passage of the Civil Rights Act of 1964.
After the relics of the Philadelphia gunboat were salvaged in 1964, they were transported to the museum.
The Philadelphia gunboat relic, built in 1776, had lain at the bottom of Lake Shangpulan since its sinking until it was discovered in 1935.