If you don't have a VALID passPORT, get or renew it ASAP; even if you THINK you won't need it (example: you have a family emergency in another country, and you need to get the next flight out. NO valid passport = NO travel to foriegn countries by air).
To the OP, Don't try to save a few bucks by only getting the passcard (passport card), if possible get BOTH the passPORT (passport book) and the passCARD (passport card for LAND and SEA crossings ONLY between a few countries tightly allied with the USA); and make sure it's VALID (not expired, not voided etc.). A passport book also serves as another form of widely accepted ID incase you misplace or lose your state ID.
Infact after I submit this post I'm checking both my passport book and card for expiry dates, and maintaining them accordingly. I don't like the "papers please" system, I just have to follow it if I want to enter other countries legally & hassle free.
TLDR, Get or renew your PassPORT book ASAP, it's insurance for when you need to fly to foreign countries on very short notice.