Back in the 70s, the federal Office of Technology Assessment calculated the effects of a bomb hitting Detroit, and Leningrad. It wasn't a pretty picture, and nearly 40 years later, it's still chilling to read.
That cover pictured above is from a reprint of the OTA's report, which you can buy in paper if you want, but the online PDF copy is free — as are dozens of other interesting OTA studies of the impact of technology in the 70s, 80s, and 90s, before the office was disbanded in 1995. It's great that the Federation of American Scientists have put this archive online!