More than six tons of confiscated ivory including tusks, carvings and jewellery have been crushed in the US.
Thousands of items accumulated over the past 25 years were dumped into a steel crusher at the National Wildlife Property Repository north of Denver.
The items were seized from smugglers, traders and tourists at US ports of entry since the 1989 international embargo on the ivory trade took effect.
Elephants continue to be shot for their prized tusks despite the global ban.
“These stockpiles of ivory fuel the demand,” said Dan Ashe, director of the US Fish and Wildlife Service.
“We need to crush the stores of ivory worldwide.”
Mr Ashe said keeping the stockpile could feed consumer demand for illegal souvenirs and trinkets.
Officials said the collection represented the killing of more than 2,000 adult elephants.
The illegal trade in ivory threatens the very existence of the African elephant, the largest land animal on Earth, experts have warned.
Last year saw the highest number of large seizures of illegal ivory for more than two decades.