Good (fictional) locations for a Post-Apocalyptic Stronghold?

How many people have survived? Go with the underground salt mines in Hutchinson, KS. It would definitely be different (the races of people living in the subway systems are overdone anyway). A vast expanse underground, the Hutchinson Salt Company mine covers about 920 acres. If one were to consecutively line up each excavated area, the chamber would stretch for 67 miles.