Here in Oklahoma it's a public record, who voted in what elections. The actual vote is secret I belive. We used to use this info,when we were mailing out candidate info,to save money and only mail to likely voters.

Years ago me and my brother were very active in the republican party,he managed the data base and printed the labels on one of the old dot matrix printers. He had that thing cranking 24-7 and we had groups of old people putting the labels on. I ran around picking stuff up at the printers and delivering the labels and material.

We ran local campaigns on next to nothing.