What is the meaning behind the bumper stickers I keep seeing.It is a black background with a blue sripe in ctr

Question

Some are small stickers with an "A" in the middle.

Answer 1

Could be the sticker cops use to identify themselves to other cops. It's called "Thin Blue Line". Cop pulls over a car, sees it as they approach, turns around and leaves.

Answer 2

I haven't seen the bumper sticker, but the only thing that I know of using the initials CTR is religious, meaning Choose The Right.