In late August 1619, a ship arrived in Point Comfort, near the city of Jamestown, in the British colony of Virginia.

Onboard were "twenty and odd" Africans, who were traded for "foodstuffs".

They were considered to be the first Africans forced into servitude in what would become the United States of America.

How the slave trade exploded in the 1600s

The transatlantic slave trade began in the late 15th century, with Portuguese ships transporting enslaved Africans to work in sugar plantations in Cape Verde and Madeira. Soon after, slaves were brought to Brazil by the Portuguese and to the Caribbean by Spanish conquistadors.

British, French and Dutch mariners quickly joined in.

It is believed that a few hundred thousand Africans were forced into slavery in the Americas before 1600. But that figure soon exploded as sugar and tobacco plantations grew.

In Virginia, for example, the labour force had primarily consisted of white indentured servants before the 1619 arrival in Point Comfort. But, by the 1690s, there were four times as many enslaved Africans as white servants.

Overall, between 10 to 12 million enslaved Africans were forced to make the transatlantic voyage. Britain and Portugal were the most prolific slavers, accounting for 70% of all Africans taken to the Americas.

Britain's national archive estimates the country transported 3.1 million Africans to its colonies — including in the Caribbean and North and South America — between the 16th and 19th centuries.

Only 2.7 million arrived because of the deplorable conditions on board ships, which saw many succumb to illness and disease before they arrived.

The state of Vermont, then a self-declared republic, abolished slavery in 1777. Several other northern states, including Pennsylvania, Massachusetts, New Hampshire, Rhode Island and Connecticut, had by 1784 also enacted laws for the progressive emancipation of slaves.

Abolition was eventually enshrined in the American Constitution in 1865, but not before the United States fought a four-year civil war primarily over the issue of slavery.

How the legacy of slavery continues to have an impact

Four hundred years after that Dutch ship arrived in Virginia and 154 years since its abolition, slavery — and its legacy — continues to have an impact on the social, political and economic makeup of the U.S.

A study from the Pew Research Center released earlier this year found that six out of ten Americans believe slavery continues to hamper the status of black people. Most (45%) also said that the country hasn't gone far enough in giving black people equal rights with whites.

A majority of respondents — whether white, black or Hispanic — also said race relations in America are bad and actually getting worse.

African Americans and, to a slightly lesser extent, Latinos are more likely to experience poverty than their white counterparts, according to the American Psychological Association, while their children are more likely to attend high-poverty schools with fewer resources and a less rigorous curriculum.

More than 12% of African American college graduates between the ages of 22 and 27 were unemployed in 2013, double the rate for all college graduates of the same age range.

And there are also important health disparities: Black children have a 500% higher death rate from asthma compared with white children and African Americans, in general, have higher rates of diabetes, hypertension, and heart disease than other groups, Harvard professor David Williams and Risa Lavizzo-Mourey, CEO of the country's largest health care foundation, claimed in a US News op-ed in 2016.

Lifting the veil of mystery

But for many African Americans, the issue is one of identity and heritage and the difficulty that they have tracing family routes back beyond the era of emancipation. In many cases, medical records are lacking for individuals that were considered commodities rather than human beings.

Only modern technology, including DNA testing, has enabled the veil of mystery to be lifted slightly.

Professor Tani Sanchez, an African American from Los Angeles, and her daughter, Tani Sylvester, travelled to Ghana this month after genetic testing showed a direct link between Sanchez's great-great-grandfather and the Ashanti ethnic group in the western African country.

There, they met Ashanti Kingdom chiefs and visited the Assin Manso river where slaves took a final bath before imprisonment on the coast.

They also visited the harrowing Cape Coast Castle where slaves were chained in dungeons before walking through the 'Door of No Return' to board the ships that brought them to America.

"I feel much more connected and I look at people and I say oh my goodness, you know, that could have been, these people could be related to me, these people probably knew my grandmother's grandmother's grandmother," said Tani Sanchez.

"I mean it just blows me away and then to actually meet groups that are identified through DNA. I just felt like it wasn't a coincidence,"

For Sylvester, the experience was also transformative.

"This is my home, this is where I am from," she said.