If you examine a postage stamp from the United Kingdom you will note that
the name of the country is missing. This is a commonplace of philately.
Likewise I believe it is a supportable convention to abbreviate topic
titles such as Paris, Texas or Saguache County, Colorado or even simply
Dorset or Yorkshire. There is a slight objective problem for those who have
some English but are not throughly familiar with English language popular
culture. Somehow adding USA or England on to the examples seems quite
awkward.
The convention for the reader is that if no country is mentioned the United
States or Britain can be assumed.
Fred Bauder