I would probably stop at the age of 12 or 13
I'm 50 and still go trick or treating! Age isn't the determining factor it is the ability to still trick or treat!
Start age 1 and end age NEVER!
Years ago children would wear their father's work clothes or dress as a clown or their favorite cartoon character. They could walk miles, with their brothers and sisters without ever having to worry.
Today, many of the costumes worn by children are to say the least horrifying. I am not so sure that I haven't arrived at a scene of an accident, instead of opening the door to "trick or treaters".
For this reason alone, I would make sure that I took my small child to an "organized" trick or treat or "Harvest Party". They are generally offered by private clubs or churches. These organizations attempt to keep the atmosphere less violent and encourage the trick or treaters to dress in "cute" costumes, instead of angry or violent ones.
OR just take the younger child to the homes of family and friends.
I am assuming YOU intend to take the child? It will be a wonderful memory for both of you!
LASTLY....do not allow your child to eat any candy or food that is "unwrapped".
It IS a sad old world we live in, isn't it?
HOW OLD IS TOO OLD? I don't know...I would STILL go if I had a child and I am 57, ha
Whenever you want to I stopped at 35 just because of laziness LOL but other then that I still loved to go trick or treating I didnt ever think about my age. Just wear a costume that covers your whole body and face no one will ever know. Happy trick or treating
Kids should start and stop trick or treating when ever they want to.It doesn't matter when somebody starts or even stops.they don't even have to stop.