From the Riverside County Registrar's Office:
To ensure that ballots reach election officials in time to be counted in Tuesday’s election, voters should not return their ballots by mail after tomorrow (May 28).
After tomorrow, voters are encouraged to return their ballots to drop-off boxes in participating city clerks’ offices through Monday (June 2) or at any polling place in the county on Election Day (June 3). A link to the location of the drop-off boxes is available on the Registrar of Voters’ website at www.voteinfo.net or you can call (951) 486-7200 for more information. Ballots can also be deposited in the 24-hour drop box outside the front entrance of the Registrar of Voters’ office at 2724 Gateway Drive in Riverside.
Ballots must reach the registrar by 8 p.m. on Election Day to be counted. Ballots postmarked before the deadline are not accepted and cannot be counted if they reach the registrar’s office after the 8 p.m. deadline on Election Day.
Interim Registrar of Voters Rebecca Spencer encourages every eligible voter to cast a ballot in the election.