backpacking alone

Perfectly safe. Or rather, safe the same way that New York is safe; the odds of something happening to you as an individual visitor are very low. Your current phone may work in Europe, or you can get one there (like the "go phones" or "throwaway phones" sold in the US). Assuming that by "Manhattan" you mean New York City and not KS or somewhere else, you already know all about how to "stay safe." You won't be counting large amounts of money in public; you won't be stopping to listen to someone who wants money from you; you won't be playing 3 card monte just because you saw someone else win; etc.

Stay away from the sex trade, remain relatively sober, and avoid big soccer crowds. Other than that, as a young male, you have little to worry about unless you present a criminal with an easy opportunity. Cheap pay-as-you-go cell phones are available throughout Europe, and they work on the entire continent.

Beware the moors. Stay on the path. http://www.youtube.com/watch?v=Hb7zhYzenhY

That was funny Karen. Love that movie!!

Your most likely issue will be with pushy tourguides in museums who think that his/her group owns the place just because they outnumber you.

Oh yes Herold, it is Manhattan, KANSAS. Thank you all for your info.

Do it!! Your life will have such great memories and you will have a grand time!!!

Karen: When I read D.R.'s question, that was my first thought too! D.R.: Since you're not from a big city, you will have to make one major adjustment: you will have to learn to be "rude." When a stranger approaches you, you will have to learn not to be afraid to say "No thanks" and walk away. It's very hard for many Americans to ignore people, as it's been beaten into us that it's "rude." But when someone you don't know wants to talk to you in a big city, they're usually trouble. Whether it's a ring that they just "found" (if you give them a small deposit you'll get rich reselling it!) or a petition that they want you to sign (while you're distracted, someone can pick your pocket) or a game they want you to bet on (one of their friends just won, but, shockingly, when you play you lose), they're all scams or trouble of one sort of another. There's no need to be actually rude - don't yell, curse, get angry, etc. But just say "no thank you," and then ignore them. If they continue, then they are being rude, so don't respond to any attempts at a guilt trip - just keep walking. As for the phone, your US phone may work in Europe, and while this can be expensive (over $1 a minute), it's fine if you're only planning on making a few calls. If you tell us your carrier and phone model, we may be able to figure out if it will work.