In 1928 the Republican National Committee put out a 
pro-Hoover ad, saying that he would continue the
prosperity begun by Harding and Coolidge who "...put a chicken in 
every pot.  And a car in every backyard
to boot." http://hoover.archives.gov/info/faq.html  At that time 
Americans were eating an average of a half
pound per year.  By the end of WWII that had increased to 5 pounds a 
year and is currently 90 pounds per year.
Until 1910, most were apparently raised for show.  Note that the 
attribution is to the campaign for Hoover, NOT to
Hoover himself.  Nor was it a promise to provide so many chickens and cars.

           Only by about 1910 did raising chickens for eggs supersede 
raising them for exhibition.
  http://www.birdflubook.com/a.php?id=66  Yeah, it's an odd source, 
but is thoroughly referenced.  Might be
interesting to trace some of the references to their sources.

           http://www.newsobserver.com/105/story/509528.html provides 
some background on how that growth
started...but doesn't tie directly to the RNC ad.  I didn't happen to 
find a site that considered the (especially rural)
home raising of chickens for eggs and meat.

           I'd suspect that a lot of the chickens for dinner were 
from flocks home-raised for eggs and were
hens that had ceased laying, hens that didn't start laying, and eggs 
allowed to hatch, to, among other things, replenish
the flock, especially the young roosters - after all one only needs a 
single rooster for a considerable flock and about
half of all eggs will hatch out males.

           Amazing what one can find by goggling a phrase!  Didn't 
ask my grandparents - last one died, at age 96, in 1954.

RCL