Nice comparison from the Economist!
It has long been true that California on its own would rank as one of the biggest economies in the world. At present it would rank 8th, falling between Italy and Brazil on a nominal exchange-rate basis. But how do other American states compare with other countries? Taking the nearest equivalent country from 2009 data reveals some surprises. Who would have thought that despite years of car-industry hardship, Michigan's economy is about the same size as the whole of Taiwan's?