Growing Independence

My kids are so lucky to have an amazing amount of cousins to play with.  We have a big family that in the last few years seems to have grown excessively.  This weekend they got to spend time with quite a few of those cousins. 

We spent the last two days at Andy's grandparents ranch where for the first time Emily was extremely independent.  She and her favorite person for the weekend, Garrett, ran everywhere together without needing Andy or I to go with her.  Although it was nice to not be needed, I found that I might not be ready for that independence regardless if she is.  I was constantly afraid of her wandering too close to the horses (which she is afraid of) or going to close to the river (which is gated).  It is all unwarranted fears and I know it is my own issues of letting her go.  How did you deal with your kids becoming independent?