Preheat oven to 425 degrees.
Butter one 9-inch by 5-inch by 3-inch loaf pans. In a medium bowl, combine flour, baking powder, salt, and sugar. Add cornmeal and blend well.
In a separate bowl, combine and beat milk, egg, and butter.
Pour the wet ingredients over dry mixture. Stir to blend. Fold in the blueberries.
Pour batter into pans.
Bake for about 50 minutes. Cool corn bread on rack for 10 minutes. Turn out onto rack to cool completely. Refrigerate wrapped for 2 days, or freeze for 2 weeks.