The first Welsh families arrived in Ohio in the early 1800s, settling in an area of fertile land with hills and valleys, and an abundance of timber and natural springs, which is said to have reminded them of home.
Orlo Price, Lithgow’s grandfather on his mother’s side, was one of eight brothers who settled there.
“It was almost like a ‘How Green Was My Valley’ story,” Lithgow told Lucy Owen on BBC Radio Wales.
“They all came over together in the 19th century to settle in the Welsh Hills of Ohio, near the town of Granville.”
Oscar-nominated Lithgow grew up in southern Ohio, but remembered travelling to the Welsh Hills.
“We’d visit the Price relatives in these rolling hills covered with peach trees and apple trees,” he added.
“It was like visiting Wales.”
Despite the family connection, he said he’s only been to Wales once.
He said: “I remember making a destination trip to Caernarfon when I was a drama student. But apart from that I have not been back to Wales to my shame.
“It’s sitting there, waiting for me to go seek out my roots.”