some countries aren't looking for visitors or, more specifically, American visitors.

1. Iran: Backpacking through Europe and want to hit up Iran on your way home? You sound cool! But it’s not going to be that easy. There’s no Iranian Embassy in the U.S., so you’ll have to go through the Pakistani Embassy in DC. Then you’ll have to go with a group tour or private guide. Then wait a couple months to see if you get a visa. I hope you’ve never been to Israel or they won’t let you in, and if you’re of Persian descent you're better off not going or they might not let you leave.