"I would walk 500 miles...."
The farthest would have to be the Italians in my tree seeing as that's a bit farther away than say France/Canada or England. Traveling from Naples, my four great-grandparents on my dad's side (Vincenzo Ferraiolo, Maria Tedesco, Giuseppe Carrabs and Clementina Forgione) would had to have traveled from their respective towns of San Pietro a Maida and Gesualdo to Naples, to New York and ultimately Haverhill, Massachusetts. Let's break the distance down.
From San Pietro a Maida to Naples is 359 kms (223 miles)
From Gesualdo to Naples is 104 kms (64 miles)
From Naples to New York is 4,399 miles
From New York to Haverhill, Mass is 235 miles.
So, if I add this all up. The Ferraiolos traveled a total of 4,857 miles. The Carrabs family traveled 4,698 miles.
That's a lot of traveling. Most of the travel time was taken up by crossing the Atlantic by boat. Clementina and Giuseppe only did it once and when they got to Haverhill she told him. "Never again! Are you out of your mind?!" I think more curse words were involved. Clementina didn't like traveling. Vincenzo on the other hand went back and forth several times over the course of his life once airplanes were more widely used.
It looks like the Ferraiolos traveled the farthest. But, keep in mind Vincenzo and Maria never traveled together. Maria left Italy with her kids, my grandfather and my great-aunt. So, she had to deal with two kids under ten while crossing the Atlantic. Vincenzo met her in NY and they drove to Haverhill. The rest, as they say, is history.