White rhinos will join four other species -- the Javan, black, Sumatran, and Indian rhinos -- listed under the Endangered Species Act and will now be considered "threatened," which bars their sale and trade in the United States.
"This new action prohibits the sale or offer for sale in interstate commerce of this species and its parts and products, consistent with all other rhinos," the U.S. Fish and Wildlife Service said in a statement.
The United States is a major center for the rhino horn trade, and products often move through the country en route to South East Asia, conservationists said.
The United States has the greatest number of trophy hunters importing horns as trophies, Teresa Telecky, director of wildlife for the Humane Society International, told Discover News.
Between 2002 and 2012, Americans imported 116 horn carvings, 206 horn pieces, 63 horns and 688 hunting trophies, figures from the USFWS show.
Many of those trophies find their way to China or Vietnam, where the horns are highly prized for their supposed medicinal properties, beliefs not supported by any science.
"The reason that rhino poaching increased so much over the past six years, and continues to rise, is that there is growing wealth in Vietnam," Telecky said. "More people are able to afford to buy rhino horn now than ever before."