Complex sentence: The Association provided land at low cost, and financing for those who would develop it, to aid freedmen and Negro refugees, who usually reached Canada via the Underground Railroad from the United States in the years before the American Civil War.
Split into simpler sentences: The Association provided land at low cost, and financing for those who would develop it, to aid freedmen and Negro refugees. These former slaves usually reached Canada via the Underground Railroad from the United States in the years before the American Civil War.