Can an independent vote in a primary election?
Yes and No. In Iowa, you must be a member of a political party (currently: Republican, Democratic, and Libertarian) to vote in a primary election. However, anyone* can change parties on Election Day and vote. For independents to vote they must declare a political party.
*Precinct election officials may not change political parties within 30 days of an election.
Do I have to register to vote for every election?
No. You would only need to re-register if your information has changed and you need to update it.