'Lucy' will be the star attraction of 200 other Ethiopian exhibits that will tour museums in 10 US cities from September 2007.
"Lucy has been in Ethiopia over the last 30 years," said Gezahgen Kebede, Ethiopia's honorary consul in Houston, Texas. The exhibition begins at the Houston Museum of Natural Sciences.
Hominids are primates who split from apes between five and seven million years ago. They are considered the forerunners of anatomically modern humans, who appeared about 200,000 years ago.
"It is time for us to share her with the whole world because she is the origin of mankind," he told AFP.
Lucy was discovered by American paleontologists Donald Johanson and Tom Gray in 1974 in Ethiopia's northern Afar region.
Named after the Beatles' song 'Lucy in the Sky with Diamonds,' she was taken once to the United States for lab tests; but ever since has been stored in a special vault at the National Museum of Ethiopia, Addis Ababa. A replica of Lucy is on display at the museum.
Gezahgen said he hoped Lucy would help alter Ethiopia’s image. The Horn of Africa nation is perhaps better known to the outside world for famine, floods and human suffering than science.
"The idea is to promote Ethiopia in a positive way," he said.
"We have a lot of attractions but it is not well known abroad, where images of drought and poverty are still dominant."
Lucy, part of a hotly disputed branch of the human tree known as Australopithecus afarensis, was the earliest known member of the hominid family for over 20 years.
Once thought by some experts to be our ancestor, A.afarensis is now widely considered to be a failed branch of the human tree. Many experts suspect the hominid was anatomically far closer to apes than humans.