Adults at least 21 years of age who are not residents of the United States may bring in, free of duty and internal revenue tax, not more than one liter of alcoholic beverages beer, wine, liquor for personal use. [...]
In addition to U.S. Federal laws, the traveler must also meet state alcoholic beverage laws which may be more restrictive if the state in which you arrive permits less liquor than you have legally brought into the United States, that State's laws apply to your importation of alcoholic beverages.
The first part is fine, I take 2x0.5l and am fine. But the second paragraph makes it complicated: How can I find the appropriate rules?
Is there any other paper work I have to mind or can I simply pass border and customs control?
I fly via Philadelphia, PA to San Francisco, CA.