Pewter is a metal alloy of tin and lead. Some of the pewter made after 1840 has a slightly different composition and is called Britannia metal. American pewter was made as early as 1639. This later type of pewter was worked by machine; the earlier pieces were made by hand. In the 1920s pewter came back into fashion and pieces were often marked Genuine Pewter. Eighteenth-, nineteenth-, and twentieth-century examples are listed here.