In the 70's I was allowed to walk to school [3 blocks from my house] and only with other children. My mother impressed upon me that it was alright to go, but only with another adult whom I knew, or a group of children. I was allowed to walk to my great grandmothers house and my best friend lived next-door to her [2 blocks away] but only if my mother walked me to the top of the street where she could watch me make it to their houses, and I was to call when I was coming back, unless escorted by one of the adults, or coming with my friend.
Traffic crossings and strangers were always emphasized...we all know the lecture there.
In the 80's [after I was 10] I was allowed a large paper-route I shared with a friend, my job at the top of our street at a corner Mom'n'Pop convenience store...anything within the block I lived was pretty much my realm of 'freedom' as long as she knew where I was at every turn, and/or had friends with me.
It wasn't until I was 12 almost 13 that she allowed me to be about on my own. Still with really strict marching orders on what to do if this or that.
The way the 'crazies' are these days, I think I would find it much harder to trust anything with a childs' independence until a later age.
Though it's important to him to be a "big boy" and do things on his own, you as a parent realise much more readily than he, just what the dangers are that are out there. In that you are asking the question, it sounds maybe as if it still scares you a bit...follow your gut. You're his parent and know in your heart and the pit of your stomach...maybe it doesn't sound like such a great idea, not just yet.
I think the suggestion above about saying yes, and following at a safe distance, could sound like a good one, but, if he catches you, he'll be pretty angry that you said yes and then didn't trust him.
Maybe you could make the same suggestion to him, in that "how about this...Mommy wants to take a walk, and if it's alright for now, because Mommy is nervous, you let me walk you to "X" point, and just wait for you to go and come back [some place where you can keep him in your line of sight], and maybe once Mommy feels a little better, we can try letting you go on your own." ??? I don't know...maybe it would work, because then it's a compromise...he's still pretty much getting his way, and you are as well.
These days, I don't know that I could buy any statistical information about how many kiddy pervs live in any given community, or what community is considered 'safe'...because as I see it, no community is ever safe...it just takes the wrong place, wrong time, the wrong person wandering around, and a spare moment to hurt your child.
A bit off subject, but as an example: I lived in a small 92 home community. Everyone knew everyone, it was quiet, people could leave their doors unlocked, it just seemed like the perfect neighborhood. My parents and I lived next-door to a state police officer [everyone knew it, knew him], I came home one night after being out, parked my car up against the garage, locked it [habit from being at work, wasn't worried about home], the dog barked once that night, I woke up the next morning and went to bound out into my car and get to work...someone had jimmied my car door, and stole my stereo. No one in my neighborhood would have done it, I fished with all the local boys and they were friends...someone from the outside, wandered in...and stole my stereo.
I hope that you find amicable ground, where you can keep peace of mind and your son can 'get a feel' for his independence as a 'big boy.'
Good luck!