How Old Is Old Enough to Walk to the Park Alone? [POLL]

Last month a Florida mom was given a ticket for letting her 9 year old son walk to the park by himself. She equipped him with a cell phone and checked in with him, but police still deemed her neglectful. I think (in today's world) any smaller than 13 is too young to go walking down the street by yourself. 

These thoughts stemmed from a conversation about whether kids today are as mature as kids 30 years ago. We all walked to the park -- heck, some of us walked to Hermiston -- by ourselves. But kids today have more distractions. And I think there are more risks than before. Hmmm. these are my thoughts. What are yours?