A more or less open voting ledger already exists without a blockchain. You can go to your Secretary of State and buy the record of voting in your state for some

A more or less open voting ledger already exists without a blockchain. You can go to your Secretary of State and buy the record of voting in your state for somewhere between 0 and a few thousand dollars. You could also buy it from a private company which aggregates and resells that data. The only information not available is how particular individuals voted.