Historically and genealogically, the Maritime Provinces of Canada and the northeastern United States share a lot. Both areas were being settled by Great Britain during the same period, and people coming direct from England and Northern Ireland met "planters" from New England enticed north by the promise of developed lands from which the French had been forced by the British. Some of the Planters stayed only a short while, some stayed a generation, and some became "Canadians."
Both areas were impacted by the American Rebellion, particularly with the influx to Canada of New Englanders forced out of their ancestral homes by the rebels. After the war, people moved freely between the two areas, and often did not completely settle in one place or the other. Economic hard times in the Maritimes brought major numbers of Canadians to "the States," especially to the developing lands in Wisconsin, Minnesota and Michigan.
If you are "missing" members of your Family Tree, Canadians might profit by looking South, and those in the United States might be rewarded looking North.