U is for U.S.A. Pottery

 Vintage pottery marked USA is not pottery made by a specific company.  It was, in fact, a patriotic gesture resulting initially from the Great War (WWI, 1914-1918) and later from WWII (1939-1945) whereby companies proudly identified with their country of origin.  The  McKinley Tariff Act of 1891 required country of origin identification on all products imported into the US.  However, marks could include paper labels which oftentimes fell off making it difficult to identify the country.  Most USA marked pottery was manufactured by Shawnee Pottery and McCoy Pottery. The best way to learn more about this vintage mark is to familiarize yourself with these potteries and their wares.  Happy Hunting!