POD 1830, Irish immigrants to the Columbia River Valley write glowing reports to their families back home.
When the Great Potato Famine strikes during the 1840s, so many Irish emigrate to Oregon that they dominate the state .... population-wise.
It helps if East-Coast cities like Quebec, Boston, New York and Philidelphia refuse Irish refugees.
ITTL many thousands travel as indentured labourers, but better nutrition and milder climate mean that most survive their indenture.
Does the Catholic Church help organize refugee ships?
Do Orangemen organize refugee ships?
Do Irish Catholics dominate O'Reagan?
Do Irish Protestants dominate O'Reagan?
Does anyone care which church your grandfather prayed in?