The "Made in Japan" marks do not necessarily date to Post 1921.
 Costello and Maniery found these marks in 1915 fire deposits in Walnut Creek
California and they cite additional sites with "Made in Japan" used earlier.
 It would strike me that the use of the word "Japan" is much like that
addition of England to marks...Just because the McKinley Tariff Act required
its use after 1891, that does not mean the country name was use prior to that
date.
 
Costello, Julia G. and Mary L. Maniery
     1988     Rice Bowls in the Delta:  Artifacts Recovered from the 1915
Asian Community of Walnut Grove, California.  Occasional Paper 16, Institue
of Archaeology, University of California, Los Angeles.
 
Erica S. Gibson
Sonoma State University