Yes, you probably can be located when you place a phone call, or even if your phone is just on. In fact, it's the law.

In the United States there is a mandatory obligation for wireless carriers to be able to locate you precisely when you call 911. You should not worry about that compromising your privacy though. All operators have to follow stringent rules of privacy and will therefore be very careful to remain lawful when using private information such as your location outside of the mandatory requirement.