I had a single key that I put in my wallet and so you could see the key outline after a while. I was 10 when I started riding the bus home alone and staying home alone (basically when parents wanted to stop paying for after school care, both worked outside of the home) and I had to call to check in when I got home and I was supposed to stay in doors and not answer the phone until they got home.
By 12 I was allowed to go out when home alone and generally ride my bike wherever i wanted, which was functionally around 2 miles because round trip 4 miles in the city fighting busy roads and crossing overpasses sucked.
Then I got my bike stolen at a putt and place type arcade, so I hoofed it around then.
At 12 we neighborhood kids started smoking Marlboro lights. So between rollerblading and camping out at the Diamond Shamrock looking for young adults who looked cool enough to buy us our $3.00 Marlboro lights in a box, we walked around so we could smoke cigs and then later pot.
Then we got cars and fake IDs and getting drunk became our god.
The life of a latchkey kid.