I found this Reddit post fascinating and cool.
It would appear that in New York City, $100 would only buy you 6 days worth of food. Living in Kansas City, Missouri or Des Moines, Iowa your $100 would stretch further to 11 days of food. Out of the USA, $100 can stretch further. My wife's friends is from Bogota, Colombia and she would see that $100 stretch to 24 days of food!