In what month of 1948 was Andrew Wyeth's painting "Christina's World"
first on exhibit at the Museum of Modern Art?

December.

According to a New York Times article dated December 26, 1948,
"Christina's World" was "recent acquisition" for MOMA and went on
display in an exhibition that had opened the previous week.  The photo
of the picture is prominently featured in the NY Times' article.

The article citation is:

NY Times
Dec 26, 1948

Today's Americans
The Museum of Modern Art's Collection
--Artists' Gift to Israel's Museums


A librarian should be able to help you obtain a copy of the original
article, if that is of interest to you.

Let me know if you need any additional information.

pafalafa-ga


search strategy:  Searched the NY Times archives database for "Christina's World"

Was it exhibited in the Moma in 1948?  This site  
http://camden.k2bh.com/Community/Story.cfm?StoryID=3886
says the director of the moma purchased it in 1949, and that it was
last exhibited in the Farnsworth gallery in 1951.  The painting could
have been on loan and exhibited in 1948, and then the director
subsequently decided to buy it with the agreement that Farnsworth
could exhibit it, maybe as part of an exhibition of the artist's
works.