Archibald T., known as Tom, was the son of Hannah Lawson and Archibald MacIntyre of Twiggs County, Georgia, and moved with his parents to Thomas County, Georgia, when still a child. He was admitted to the bar in 1843 and practiced law in Thomasville. Tom served in the Georgia General Assembly, as a delegate to the State constitutional convention in 1865, and represented his district in the U.S. House of Representatives, 1871-1873. MacIntyre was colonel of the 11th Regiment Georgia Guard during the Civil War. Late in life he served on the boards of the Georgia State Sanitarium and trustees of the University of Georgia.

Tom MacIntyre married America Young, who bore him six children. His son, Archibald T., Jr., (1852-1897), was also a lawyer. Because he died relatively young, his wife, Margaret Fraser Livingston, and son, Hugh James MacIntyre, are more heavily represented in the collection than their husband and father.