New York in the 1970s was the gritty New York that city has been stereotyped as since. Crime was high, and Central Park was avoided at night for fear of murders and rapes, and the Subways and Streets were avoided because of muggings (and the subways frequently broke down due to neglect anyway). The Son of Sam killer was at large. Sex shops, peep shows and pimps, prostitutes, and drug dealers were in Time Square and throughout the city, and the drug dealers, prostitutes and pimps were doing their illegal activities right in front of the police. The police force was corrupt, which was revealed by Frank Serpico. The city was also hit hard by the economic downturn of the 1970s, and nearly went bankrupt. Because of the deterioration of the city, masses of the population were also leaving. It would take years for the city to recover, and almost twenty years for the city to recover its lost population.
For as bad as things were in the OTL, just how bad could it plausibly get?