Karo (or at least some form of corn syrup) is a crucial structural element in many pies. Having two different types of sugar that don’t easily crystalize together avoids the sugar hardening in random spots.
From a box sold in Louisville, Kentucky.
Karo Pecan Pie
2 eggs
1 cup Karo syrup
1 tsp. vanilla
1 cup sugar
2 Tbsp. margarine or butter
1 tsp. salt
1 cup pecans
Peanuts or coconut may be substituted.