I was over in the USA during the summer and I was shocked with their lack of credit card security.
As previously mentioned, there is no Chip and Pin in place which I find bizarre when I have been in what you might call 3rd world countries which have it in place but a country as advanced technologically as USA doesn't have it.
Even worse, they don't always ask you to sign a credit card slip either; in many of these cases they looked for an ID but in at least two occasions, I wasn't.
Petrol pumps are another example; you can swipe your credit card at the pump and pay without going into the shop; no PIN number required; granted, some asked for the Zip code to be entered but others didn't.
Just be very careful with your credit cards and if you lose them, make sure they are cancelled immediately