I'm not a helicopter mom (or am I?)

My boys are getting older and the older they get the more and more independent they want/NEED to be. Especially the 9 year old. I've always been a pretty laid back mom. I didn't rush to rinse off every dropped toy, I didn't run in every time one of the made a peep and I wasn't always looking over their shoulders to make sure nothing bad happened. I let them do their thing, I wait for the tears or the blood when they fall before I run over with a bandaid. Mom's kisses and a distraction was usually all that was needed to forget about a scraped knee or bruised ego.
Helicopter parenting has been talked about a lot lately. It's not really a term I was even familiar with until recently and honestly, I kind of just shrugged it off as one of those things I didn't need to be worried about because obviously I don't fall in to that category.
Or do I?
I'm 31 years old. When I was a kid you played outside until the street lights came on, you roamed the neighborhood on your bike, you walked everywhere and anywhere and your parents kind of knew where you were. They knew you were usually somewhere in a 4 block radius and if they stood outside and yelled (as my mom frequently did) you'd better be able to hear them and you'd better get your ass home. Yet here I am with a 9 year old boy and I won't let him walk across the street with his almost 4 year old brother to play on the playground for half an hour. Why?
I tell myself it's because I don't trust the neighborhood, which is true. We don't live in a great area...but the middle of a Sunday afternoon? We tell ourselves that times are different, things have changed, strangers can't be trusted. This is likely all very true but my kids know not to go off with a stranger, they know to stay together and to watch out for each other. Why is it so hard to let them just go outside and be kids?! We talk about getting kids away from video games and tv and we want them to go enjoy being outside the way we did...and yet we don't want to give them the independence to go explore, to learn, to make new friends with the kids down the street without us on their heels trying to make sure nothing bad happens.
Today, I told my kids they could go to the park by themselves. I set the ground rules: hold hands crossing the street, look both ways, stay inside the fence at the playground and if there are older kids hanging around just come home (hey, I have limits!). Unfortunately the park was closed...but it was a big step for me.
We ended up at another park later in the day and instead of following Ian around to make sure he didn't run infront of swings, climb up slides or fall off the monkey bars I just sat down at a table, chatted with a friend and watched. Ya know what? Nothing bad happened. Sure, he fell and he climbed up the slide instead of going down it, he stood at the bottom of the slide and got knocked down, he ran and he played. He made other little friends and I didn't need to be on top of him (I will say, I'm usually not, but today I made an effort to just leave him alone). He found me when he needed something and that was that. It was nice!

So baby steps...finding the balance between being the helicopter mom and being the mom that people look at and go "omg, does she ever watch her own children?!"