Sift flour, measure and resift 3 times with next three ingredients.
Cream shortening with the sugar and cinnamon until smooth and soft.
Add the eggs and beat until fluffy and light in color.
Add the milk alternately with the dry ingredients, beating well after each addition.
Gently fold in the blueberries.
Pour into a greased 9-inch square cake pan 1 3/4 inches deep.
Bake at 350° F. (moderate) for 45 minutes, or until cake tests done.