Iowa Governor Terry Brandstad signed bill H.F. 516, which eliminated the straight-ticket device, on May 5.
Straight-ticket ballots list the officially qualified parties at the top, usually just “Democrat” and “Republican.” Voters can check an adjacent box to cast a vote for all of that party’s candidates on their ballot. Thus voters are often unaware of any Libertarian candidates who may be running.
The only states that still have the device are Alabama, Indiana, Kentucky, Oklahoma, Pennsylvania, South Carolina, Texas, and Utah; also it is still in effect in Michigan, even though it has been repealed, because a federal judge ordered it left in place, at least for 2016.
The Texas state house passed a bill to eliminate the straight-ticket device on May 6. A similar bill is working its way through the state senate.
Thanks to Ballot Access News for this story.