I KNOW what "Get out the vote!" MEANS, but it never made much grammatical sense to me. Does anyone here know the origins of this phrase and why it's worded the way it is?

BTW, I hope those of you out there who are qualified and able, really do "Get out the vote!" today, and regardless of who wins and what issues are passed, let's pull together and give the winning candidates and issues a chance once the election is over.
Peace!