I once bandied about doing a timeline, which would have included a World War II that extends well into 1946 (with the Axis getting nuked many times). The Soviet Union crumbles into a succession crisis and civil war when Stalin suffers a heart attack/is covertly assassinated after a Stalingrad-like defeat in Warsaw in 1944, while the victorious US, exhausted by the war, and finding it impossible to impose order, withdraws their troops from Europe and returns to isolationism. Without any means to stop it, Europe falls into another continent-wide civil war between communists and nationalists, armed with the leftovers from the last war, that totally destroys whatever is left of Europe's infrastructure. The war doesn't have a victor, it simply ceases because the means no longer exist to continue fighting. In the Pacific, Japan has been nuked into the stone age by 1947, while China is in the middle of a civil war between the Nationalists, the Communists, and Japanese collaborators. Many strange diseases and deformed children are noted in the eastern provinces, and large-scale famine grips the land. Africa simply goes to hell. With no foreign entities to pay their debts to the US government and the US banking system, the Depression does not get better, it gets far worse, with most of the remaining banks failing. The federal government goes bankrupt, as do nearly all businesses. With no jobs in the cities, and severe food shortages, people begin large-scale migrations to the countryside, to try their luck at subsistence farming. The last American presidential election is held in 1960, with 3000 voters. People have simply ceased to care. The population of the ruins of New York is about 30000 in the year 1970, Moscow is 40000, London about the same. Outside of the Soviet Union and Britain, there are no cities with a population above 15000 in Europe. Contact with Asia was lost in the 1950s. Humanity hasn't gone extinct, but civilization has totally collapsed, and it may be millennia before it reappears again.