Chicago is by far the worst. It's so bad I moved to Florida two weeks ago just to so I can get my gear.
Seriously, there are over a million eastern european and Russian imigrants and many are bringing things into Chicago that they shouldn't and customs is inspecting almost every package that comes through there. They are also the largest in terms of numbers. Chicago handles mail as far west as Las Vegas and east to Penn and south to KY. So they have a very big budget.