Tornadoes, Hurricanes, ice storms, all resulting in power outages, some for weeks. Flu pandemics, other disease especially brought in by illegals like TB. Food shortages from droughts, floods, storms. Economic breakdown of society resulting in hyper inflation and riots. Computer virus cutting off all food stamp receipiants with their hunger causing riots and flash mobs to steal food. An EMP nuclear blast 250 miles above Kansas from a rogue state like North Korea or Iran, would knock off most power in North America which would take about 6 months to get all power restored, resulting in no frozen or refrigerated food. No canning of food with power off, etc. No gas pumping either. Same could happen from a giant solar flare. In our high tech electrified society, we would be at the mercy of too many things to go wrong. If more people were self sufficient, had 6 months to a year's supply of food stored, could grow vegetable gardens in their yards like the WWII victory gardens, and were more civil like the 1930's, we might do alright. If the power is off over 6 weeks, many people will starve to death in the big cities, gangs of young healthy men will spread out into the suburbs and countryside looking for food. Only real way to survive is be in the countryside or small country towns with a food supply and the ability to grow and raise your own food, and weapons to protect from urban gangs coming for food. Also some type of "militia" of these rural folks to help protect each other. Having backup power like solar, wind, and generators to help keep food and to power HAM radio systems would be a big help. Also to charge batteries for walkie talkies, for communication with each other for protection. Horses might even be a premium for getting around quick.
IF power companies are or would protect themselves from an EMP blast or solar flare, that would help a lot. IF vehicles were all made with faraday cages around the electronics, that would also help. IF the government would quit paying farmers NOT to grow stuff, but use the money instead to buy up any excess food and make it into MRE's, canned or dry goods, that would also help in agricultural emergencies. IF more people prepped, that would help also. Don't know if that would happen in todays hedonistic society. Only 25% of baby boomers have any money set aside for retirement. They are also probably the preppers.