To get a sense of the pain many black Americans feel about their broken connection to Africa, just listen to the cries of joy when the divide was bridged by blacks who used DNA to trace their roots to a specific country:
"My life has been turned upside down," said Veronica Henry of Las Vegas, who quit her corporate job in information technology and set up website www.myafricandiaspora.com after she learned in 2007 that her mother's lineage came from the Mende people of Sierra Leone.
Said Stephanie Smith of Randallstown, Maryland, after tracing her roots back to Sierra Leone: "I finally feel some of the separation between myself as an African American and other Africans beginning to fall away."
Others said they were almost physically sick with anticipation as they opened the envelope containing their DNA test results that could reveal their ancestry.
Since DNA mapping made it possible to trace ancestry, tens of thousands of people around the world have taken tests. But the process is of particular interest to black Americans because it offers to reverse the terrible forced separation from their home.
To many Africans, Barack Obama's trip to Ghana starting Friday will represent a homecoming for the first African American president and he will be welcomed as a son of the world's poorest continent who has attained global power.
Obama's heritage includes Kenya and his father came to the United States as a foreign student, but the trip will also generate interest in the success of other blacks in retracing their roots.
One effect of the slave trade that flourished between the 1600s and the 1900s transporting around 10 million Africans to the Western hemisphere, including 4 million to the land that became the United States, was that black Americans almost never knew which part of Africa they came from.
"I always felt like a fake or an intruder if I tried to join or participate in heritage festivals or cultural conferences that focused on a particular place in Africa, say Ghana, Senegal, or Kenya for instance," said Smith about her experience prior to tracing her roots.
"Now I feel like I belong," she said.
Veronica Henry is trying to formalize the reconnection by applying for Sierra Leone citizenship to go along with her US citizenship.
Tracing involves taking a swab of DNA and analyzing the resulting mitochondrial DNA for maternal lineage or the Y-chromosome, which only men carry, for paternal ancestry, said geneticist Rick Kittles of the US company African Ancestry, which focuses on tracing roots for black Americans.
The company says it has successfully conducted 15,000 tests since its launch in 2003, but because matrilineal genes spread to all female members of a family it calculates 100,000 Americans now know their African roots.
Scholars are also interested in the DNA data to help them clarify where slaves were from.
Results show matches in 27 African countries, though they are most common to the Hausa and Fulani peoples of northern Nigeria and the Tikar and Bamileke groups from Cameroon, said company founder Gina Paige.
Obama's trip will include a tour of the fort at Elmina on Ghana's Atlantic coast. The castle contains an infamous "Door of No Return" - a small door facing out to sea - through which thousands of Africans passed in chains before being rowed out to slave ships that would take them to the New World.
But if Obama's visit generates historical interest and represents a moment of pride for his supporters, it also begs a question: how far can real connections be restored by African Americans seeking their roots?
"I hate to say this but in many ways black Americans are resented in Africa," said Andrew Young, a former US ambassador to the United Nations whose company, GoodWorks International, has for decades done business in Africa.
"A lot of times they (African Americans) bring this on themselves because they go back to Africa like they belong and in their minds they do belong, but not in the minds of the governments," said Young, a black American who was prominent in the civil rights movement during the 1960s.
On the surface, Kalimah Johnson, a social worker from Detroit, fits perfectly the image of a naive black American happy to be at home in Africa. Johnson traced her roots back to the Akan group in southern Ghana last year.
"Ghana is absolutely wonderful. I feel like I fit right in. I love the people," said Johnson, interviewed by telephone last week during her first trip to Africa, during which she visited the capital Accra and Elmina as well as Senegal.
But Johnson said she was tempering her enthusiasm about her affinity with people there and by way of caution, recounted how somebody attempted to swindle her at the airport when she first arrived in Accra.
"I have never had this romanticized idea that the people in Africa would say 'Welcome home'," she said. But "people have treated us like royalty."