Why it matters: The primaries will determine the Republican and Democratic candidates for Congress, state Legislature, statewide offices and county judge.
The Republican primary is likely to determine statewide races.
The big picture: Democrats are seeking to retake the majority in the U.S. House and Senate in the November midterms.
How it works: Voters have to pick whether to vote in the Republican primary or the Democratic primary.
You don't have to be affiliated with either party to vote in a primary.
Key dates: Applications to register to vote must be postmarked no later than Monday.
The county is warning that a U.S.P.S. change means the postmark date could be later than the day you mailed it.