Affiliated: In some states, this means that voters must vote in the primary election of the same party as their last primary vote; loosely enforced. In other states, this means that voters must declare a party affiliation at the time they vote; they can only vote for candidates in the party with which they have affiliated.

Caucus: A public vote. Options include having voters physically congregate in various parts of a room to declare their preference and be counted, and marking a paper ballot and placing that ballot on a table to be collected and counted.

Closed Primary: Party affiliation does matter; a registered voter may only vote for a candidate in their party.

Modified Closed Primary: Party affiliation is not enforced; a registered voter can request a ballot for another party.

Open Primary: Party affiliation does not matter; a registered voter can vote for a candidate in any party.

Registration Deadline: The first date listed is the deadline for NEW voters to register. The additional date listed is the deadline for currently-registered voters to CHANGE their registration; effectively, change their party for purposes of voting across party lines.