The answers to the clues below will have something in common.

1. Fried squid
2. Hawaiian girl
3. Andean vulture
4. Upset and indignant (following "up")
5. Cup bearer of the gods and a moon of Jupiter
6. French mathematician with an eponymous triangle

Answers:

1. CALAMARI
2. WAHINE
3. CONDOR
4. IN ARMS
5. GANYMEDE
6. PASCAL

What the answers have in common:

The answer words are made up entirely of U.S. postal code abbreviations. 

Credit: 
Robert W. Harris
GOING POSTAL