why pare and not alto for stop in some countries?
Why is it that "Pare" is used for stop in some countries instead of "Alto"?
8 Answers
The verb "to stop" is "Parar". So the usted imperative would be "pare". 
"Alto" is an interjection meaning "Stop!" or "Halt!". "Pare" means "Stop!", also.
Oh my goodness...I found a thread on this topic!!!!!!!!!!!!!!!!!! Look here!
The real question is why they use S T O P in Spain 
Why do we say chips in America and they say crisps in the UK? I imagine there's some sort of detailed etymological reason... but for all practical intents and purposes, it's just whatever's in more common usage in the country.
I just returned from Mexico where the stop signs look like this:
In three weeks, I will be returning to the Dominican Republic where the stop signs look like this:
I asked a Dominican friend who said that it was an individual choice for each country. However, that has not satisfied my curiosity. After all, don't we all use the same word "stop" in the U.S., Canada, England, Australia, etc.? Hopefully, someone will answering this burning question for us and put a "stop"to our frustration. 
"Alto" is an interjection meaning "Stop!" or "Halt!". "Pare" means "Stop!", also.
But, that doesn't answer the question of why some use "alto" instead.
Both can be used. In México, the "Pare" word, isn't used often, but is more formal. Alto, is more used like an order. "Alto, no puedes entrar ahí!" Stop, you can't enter there.
Different countries, different ways, absolutely understandable in either way. We would say "pare" and so say our street signs.
In the dictionary of the Real Academia it says that "alto" is used in Central America, Colombia , Mexico and Peru. It seems them that the rest of the countries use "pare". The word "alto" comes from the German word "Halt " meaning "stop" again according to the Real Academia Española.
