$90k isn't unheard of in Seattle, either (that was my starting salary, in Seattle, 4 years ago). My alma mater published self-reported salary data and $80k was probably the median at the time. Granted, it was one of the best CS schools in the area.
Much of the east coast probably has >=$80k starting salaries as well. (Or at least, you'd expect the high salaries to be on the coasts.) Negotiate, negotiate, negotiate.
But $90k is not the norm for starting in the US. I started at $50k in DC for example post-grad school. $90k is perhaps only the Bay Area.