This volume includes 13 papers from the National Academy of Engineering's 2016 US Frontiers of Engineering (US FOE) Symposium held in September 2016. US FOE meetings bring together 100 outstanding engineers (ages 30 to 45) to exchange information about leading-edge technologies in a range of engineering fields. The 2016 symposium covered four topic areas: Pixels at Scale, Extreme Engineering, Water Desalination and Purification, and Technologies for Understanding and Treating Cancer. The papers describe leading-edge research on such topics as frontiers in virtual reality headsets, autonomous precision landing of space rockets, new materials for emerging desalination technologies, and engineering immunity against cancer, among other topics. Appendixes include information about contributors, the symposium program, and a list of meeting participants. This is the twenty-second volume in the US FOE series.