More than 1 million primary election ballots were mailed Thursday Arizona voters who requested them.

They could begin arriving at voters' households Friday.

The ballot includes all statewide offices, with primary races on the Republican side for governor, attorney general, secretary of state, superintendent of public instruction, treasurer and two seats on the Arizona Corporation Commission. On the Democratic ballot are two candidates for superintendent of public instruction; all other statewide offices are uncontested on the Democratic side.

Voters also will select Republican challengers to Democratic incumbents in Congressional Districts 1 and 2 in Southern Arizona, along with challengers in several Southern Arizona legislative races.

Voters registered Republican, Democratic, Libertarian and American’s Elect can cast ballots. In addition, voters registered with no party or as independent can vote in the primary by selecting one of those four parties and choosing among its candidates.

Independent voters make up the single largest voting group in the state.

The secretary of state's office, which oversees elections, said in a press release that the last day to request an early ballot for the Aug. 26 primary election is Aug. 15, and the ballot should be sent back by mail no later than Aug. 22. Early voters may also take their ballots to the county recorder's office or to any of several designated spots, including polling places on Election Day.

Click here for information on requesting an early ballot.

Click here to find your polling place.

Click here for Arizona Public Media's Election Center, including news and information on all the candidates, political district configurations and details on political parties.