FWIW, Liquor laws are what I've found that vary the most from state to state
PA : no grocery store sales of any liquor - only at state shops . The minimum quantity of beer you can buy is a case unless you go to a tavern -see link
VA: gorcery store can sell Beer and Wine, but "hard" liquor is sold by the state.
Also remember when I was a teen, and the drinking age in MO was 21 , but 18 in IL. Going across the river bridge late at night, there was usually two or three cop cars sitting on either side waiting for drunk drivers.