Thanks for all the comments - I appreciate the help.  
 
19 is in the plant number position, and the single number 1 is marked as
the year.  I've narrowed the date of manufacture to either 1931 or 1941
(Carol, the dot may have been abraded), but for the purpose of looking
at consumption patterns and market access, I'm trying to figure out
where plant #19 was located.  The current O-I plant #19 in Crenshaw, PA
appears to have been opened in the 1980s (from what I can tell on the
web).  I put a phone call and an email in to the O-I World Headquarters
to see if and where a plant #19 existed in the 30s-40s, but since
archaeology probably isn't at the top of their list, I may be waiting
awhile.  I'll keep everyone posted if I find a good answer.  Until then,
I've already spent too much time on this single artifact, so on to my
report...
 
Just as a side note, I've found Toulouse's work to be pretty helpful in
identifying bottles and jars, at least in the West.  The main kink is
that some of the O-I plant code numbers were reassigned in the
1940s-60s, so remembering that is important.  I liked George Miller's
comment about tracking the codes and documenting the transition from
glass to plastic containers.  Has anyone done that?
 
Thanks again!  
 
Nick 
 
 
Nicholas J. Smits, M.A.
Supervising Archaeologist
Archaeological Investigations Northwest, Inc.
2632 S.E. 162nd Avenue
Portland, Oregon  97236
Phone: (503) 761-6605 
FAX: (503) 761-6620
E-mail: [log in to unmask]