1. What do the following words have in common?

BREAD
HEAR
DEAR
STEAL

2. What do the following words have in common?

SCAR
GAME
COIN
HIND
ARMS

HINT:
2. It has to do with US geography.

Answers:

1. Each word can be followed by TH to make a new word: 

BREADTH
HEARTH
DEARTH
STEALTH

2. Each word is made up of US State postal abbreviations