PREHEAT oven to 425°F. Roll out half of the pastry and place in 9-inch pie plate. Place cracker crumbs in crust; set aside.
MIX sugar and cream of tartar in medium saucepan. Gradually stir in 1-3/4 cups water until well blended. Bring to boil on high heat. Reduce heat to low; simmer 15 minutes. Add lemon peel and juice; cool. Pour syrup over cracker crumbs. Dot with butter; sprinkle with cinnamon. Roll out remaining pastry; place over pie. Trim; seal and flute edges. Slit top crust to allow steam to escape.
BAKE 30 to 35 minutes or until crust is crisp and golden. Cool completely.
The Ritz Cracker was distributed nationally in 1935, during the height of The Great Depression. At the time, Ritz crackers were an affordable luxury. A box reportedly sold for 19 cents.