A man and his son who lived in Southern Illinois enlisted in the Mexican War in 1848 from Galena, Illinois–in the northwestern part of the state. I wasn’t certain it was him. His widow’s pension explained why they were so far from home.
They had gone to work in the lead mines.
What economic factors might have made your ancestors move? Don’t forget that even farmers may have taken an off-farm job for a while–and that may have been a distance from home.
That’s exactly what this man and his son did. After the war they returned to farming.