This chart shows the number of California voters registered to each party in ahead of the June 2016 and March 2020 presidential primaries. "No party preference" voters now outnumber registered Republicans in the state.
The California Secretary of State publishes statewide voter data 154 days ahead of each presidential primary. Data for voter registration ahead of the June 2016 primary is from Jan. 5, 2016. Data for voter registration ahead of the March 2020 primary is from Oct. 1, 2019.