What is the origin of land sakes alive?

Answer 1

From my Grandmother, which was passed on to her from many generations of family.

During the perilous journey from Europe to America many in the small ships would die from disease, malnutrition and general bad health that existed before the journey began. The trip would sometimes require months of misery at sea. At journeys end, and land came into sight, the beleaguered travelers would sometimes proclaim " Land, for the sake of God, we're alive." Thus the contraction " Land sakes alive" was very meaningful and has remained so - for generations, although the origin has been obscured by time.