Preheat oven to 400 degrees F.
Grease muffin cups or line with muffin liners.
Combine 1 1/2 cups flour, 3/4 cup sugar, salt and baking powder.
Add to the flour mixture vegetable oil, egg and buttermilk.
Fold in blueberries.
Fill muffin cups 3/4 of the way, and sprinkle with crumb topping mixture.
To Make Crumb Topping: Mix together 1/2 cup sugar, 1/3 cup flour, 1/4 cup butter, and 1 1/2 teaspoons cinnamon. Mix with fork, and sprinkle over muffins before baking.
Bake for 20 to 25 minutes in the preheated oven, or until done.
Makes 10 muffins