Under a new law, thousands of Missouri voters could have to pay $15 to acquire the documents needed to get an ID to vote. Wyoming voters also face their state’s new ID law, passed last year, which requires a government or student identification card to cast a ballot. Voters without one must present certain proof of identity to obtain the state’s free voter ID. A birth certificate there costs $25. Voter rights advocates argue these costs amount to a poll tax, declared unconstitutional over 50 years ago, and point to an array of factors that can make casting a ballot more costly for some voters.