I don't think the country was suddenly "hit" by a cocaine epidemic. It blossomed in the 1970s and 80s as part of the disco culture, but it's been around for a long time. It's use goes back to the 1800s when it was unregulated and used in all types of products such as wine, cigarettes and Coca-Cola. It hit its peak usage in 1982 when over ten million Americans were using it, and it's use has continued to rise.