These two case studies on food safety are part of the Big Cities Health Coalition's 'Big Cities Health Inventory Report: Case Studies that report on cutting-edge programs and innovative approaches to address health challenges in select cities. The first case study talks about a tool developed by the Chicago Department of Public Health to track foodborn illness complaints on Twitter. The second describes Los Angeles County's successful use of letter grading for food establishments and how they integrated food establishment letter grades into Yelp reviews in an attempt to encourage better food safety practices. FOOD SAFETY Chicago: Digital Sleuthing & Engagement to Battle Foodborne Illness (Click on view tool online fora link to a Github repository of the available code used to find foodborn illnesses using Twitter)