Letting teens travel alone on vacation

I do not like the idea of allowing teens to travel alone without a parent to another state or country on a vacation. With the way things are today I am just to afraid to let my child go without being with another adult I trust to keep an eye on here while she is gone. I know I probably sound over protective but you just can not be to careful these days. I was wondering how others felt on this subject. I welcome everyones input. I also realize that at some point in time you have to let your children grow up and do somethings on thier own. I just think that maybe when they are in college that may be a better time. I know when I was growing up I was able to take a cruise for my senior trip with my school and my parents were not overly concerned. We did have chapperones that came along but when it came to going to the ports of call we were able to go on our own. Times have changed and I know I could never let any of my children do that. Its not the issue of trusting my children it is the issue of other people. I know if something happend to any of my children I could never forgive myself. I'm sure there are people out there that have an opinion and I would like the oppertunity to discuss this further with people. I also want to hear the other side of this debate. Please feel free to express your opinion.
Thank you.