The Hill reports House votes to cut food stamps by $39 Billion.
The bill is H.R.3102 -- Nutrition Reform and Work Opportunity Act of 2013 (Introduced in House - IH).
The SNAP participants can be mapped by county at the USDA website. (Thanks +Paul Wolfe )
Find the Congressional Districts related to the SNAP participants here.
Hopefully this can aid you in concentrating your action in the appropriate districts.