Federal agents and local enforcement officers raided homes and businesses and made several arrests in a dozen states, officials said.
"By taking out this ring of rhino horn traffickers, we have shut down a major source of black market horn and dealt a serious blow to rhino horn smuggling both in the United States and globally," U.S. Fish and Wildlife Service Director Dan Ashe told the Los Angeles Times.
A global run on the rare horns from black and white rhinos, which fetch huge prices of more than $20,000 a pound when sold in places like Vietnam and China, has led to an increase in poaching in Africa.
In the United States, authorities said, traders are obtaining and illegally transporting horns from auction houses, antique shops and hunters' trophy walls.
A misconception they can cure cancer makes them "worth more than crack, heroin or gold, pound for pound," said Crawford Allan, North American director of TRAFFIC, which monitors wildlife trade.