With the Trump regime talking about a nuclear first strike against North Korea, here's a fragment of an article from Harper's Magazine, December 2017, talking about how bad things could get:
A 2006 study by the Rand Corporation calculated the effects of such a nuclear detonation at the Port of Long Beach, California. The weapon was presumed to be two thirds as powerful as the bomb that destroyed Hiroshima in 1945. According to the study, about 60,000 people in Long Beach would be killed, either by the blast or by the effects of radiation. An additional 150,000 would be exposed. And 8,000 would suffer serious burns. At the moment, there are about 200 burn beds at hospitals in California and about 2,000 nationwide. Approximately 6 million people would try to flee Los Angeles County, with varying degrees of success. Gasoline supplies would run out. The direct cost of that single detonation was estimated to be about $1 trillion. In September, North Korea detonated a nuclear device about thirty times more powerful than the one in the Rand study.