This 20-gallon Red Wing Stoneware Crock is marked Pat. Dec 21, 1915. A Red Wing Stoneware Oval reference lists 1909 to 1915 for this Stoneware Oval. It does not show anything for 1916. The next oval it shows is for 1917 and 1918. So, this crock was either manufactured late-Dec. 1915 or in 1916.