Probably all African Americans descended from slaves have a line from Ireland. Some would naturally come through an Irish slave owner on the plantation. However, it’s much more complicated than that.
There has been “free color” in America since the 1600s. It was the intermarriage and intermingling of African slave men and white indentured servants that forced laws to be enacted. Many of these women were Irish.
In Colonial America, there were questions with no legal answers. Who was a slave? How long can one retain someone in slavery? Can a Christian be a slave? What about Muslims and Jews? Can a European Christian be a slave? Is slavery color based? Were the children of an African man and a white indentured servant a slave? The answers to these questions affected the entire colonial economy in the 1600s. Over the decades into the early 1700s, these questions were answered one by one, starting in Virginia.
For those mixed-race families who were considered “free color” from the 1600s, they blended into the white, black or Indian communities. Some remained in-between as “tri-racial isolates.” Be aware that race cannot necessarily defined by skin color. Many tri-racial isolates have researched their Native American side, reorganized into a tribe, and successfully applied for state and federal acknowledgment.
American history is much more fascinating, and at times bizarre, than we were ever taught in school. All of us, regardless of skin tone can claim our Irish heritage.