The USDA just released their annual accounting of food security in the United States. Good news! Food insecurity fell to 12.7% in 2015 (down from 14.9% in 2011). Here's a key graph from the report.
One could quibble with the USDA's method of computing food security (it is based on responses to a variety of survey questions), but whatever "flaws" are inherent in the USDA methods, as long as they have remained constant over time, the trends should be informative.
Of interest is how food insecurity measures change with participation in SNAP (aka "food stamps). Using USDA data on SNAP participation, I calculated per-capita participation which is shown in the following graph. Though the pattern is somewhat similar (i.e., food insecurity and SNAP participation both rose after the Great Recession and then declined in 2015), it isn't a perfect corollary. In particular, food insecurity is higher in 2015 than in was in 1995, but today there are more participants per capita on SNAP than there were in 1995.
Another variable which might relate to food insecurity and SNAP participation is the price of food. Here is a graph of Bureau of Labor Statistics data showing the price (or CPI) of food relative to the price (or CPI) of non-food items from 1995 to 2015.
Over at the US Food Policy blog, Parke Wilde notes that even though food insecurity has fallen, it hasn't fallen nearly enough to keep up with food insecurity targets. The above graphs suggest one potential reason why: food is relatively more expensive today than was the case 20 years ago. Of course, the overall story is surely much more complicated than that.