In medium bowl, mix 2 cups flour and the salt. Cut in shortening, using pastry blender (or pulling 2 table knives through ingredients in opposite directions), until particles are size of small peas. Sprinkle with cold water, 1 tablespoon at a time, tossing with fork until all flour is moistened and pastry almost cleans side of bowl (1 to 2 teaspoons more water can be added if necessary).
Gather pastry into a ball. Divide in half; shape into 2 flattened rounds on lightly floured surface. Wrap in plastic wrap; refrigerate about 45 minutes or until dough is firm and cold, yet pliable. This allows the shortening to become slightly firm, which helps make the baked pastry more flaky. If refrigerated longer, let pastry soften slightly before rolling.
Heat oven to 425°F. With floured rolling pin, roll one round into round 2 inches larger than upside-down 9-inch glass pie plate. Fold pastry into fourths; place in pie plate. Unfold and ease into plate, pressing firmly against bottom and side.
In large bowl, mix sugar, 1/2 cup flour and the cinnamon. Stir in blueberries. Spoon into pastry-lined pie plate. Sprinkle any remaining sugar mixture over blueberry mixture. Sprinkle with lemon juice. Cut butter into small pieces; sprinkle over blueberries. Cover with top pastry that has slits cut in it; seal and flute. Cover edge with 2- to 3-inch strip of foil to prevent excessive browning.
Bake 35 to 45 minutes or until crust is golden brown and juice begins to bubble through slits in crust, removing foil for last 15 minutes of baking. Cool on cooling rack at least 2 hours.