sentence meaning - Why do you always "go down the street"

I think I hear people mostly use the phrase "going down the street" instead of "going up the street" or "going on the street"

It is common to hear that :

I was going down the street when I saw her

in songs or movies.

I don't think the word down has something do to with a inclination, declination or direction.I feel people use it even they walk on a plain road/street.What exactly does this sentence mean?

So what is the difference between :

I was going on the street when I saw her

and

I was going down the street when I saw her

and

I was going up the street when I saw her

Answer

The choice between down and up for street movement is interesting.

If the street is on a hill the usage is obvious.

If the street is on the level it is less so, but there are some rules of thumb that can be applied.

If the city has an acknowledged "uptown" and "downtown" sections, "up the street" usually goes uptown and "down the street" goes downtown.

Sometimes the choice is made based on compass direction- going North might be considered "going up the street" whereas heading South might be considered "going down the street".

Other times it's local convention- however it got established.

And a lot of times it just doesn't matter and either one is perfectly fine.

But you can get a ticket for public indecency if you are caught "going on the street."!

--get more than a ticket, you would become a sex offender Here's a link to a similar question on English Language and Usage: https://english.stackexchange.com/questions/83597/up-my-street-and-down-the-lane