AP has a history of accuracy on election nights dating to 1848.
The news agency declared Sanders the winner of the California Democratic presidential primary as soon as polls closed, even though votes from Tuesday had not yet been counted, based on results from AP VoteCast.
AP VoteCast, conducted by NORC at the University of Chicago, is a wide-ranging survey of the American electorate that captures the views of voters on whom they vote for and why.
The following is a chronology of AP’s Democratic presidential primary race calls (all times Eastern).
March 3, 2020
7:00 p.m. WASHINGTON (AP) — Joe Biden wins Democratic presidential primary in Virginia.
7:17 p.m. WASHINGTON (AP) — Bernie Sanders wins Democratic presidential primary in Vermont, scoring victory in his home state.
7:45 p.m. WASHINGTON (AP) — Joe Biden wins Democratic presidential primary in North Carolina.
8:00 p.m. WASHINGTON (AP) — Joe Biden wins Democratic presidential primary in Alabama.
9:00 p.m. WASHINGTON (AP) — Bernie Sanders wins Democratic presidential primary in Colorado; Donald Trump wins GOP primary in Texas.
9:05 p.m. WASHINGTON (AP) — Joe Biden wins Democratic presidential primary in Oklahoma.
9:30 p.m. WASHINGTON (AP) — Joe Biden wins Democratic presidential primary in Tennessee.
9:45 p.m. WASHINGTON (AP) — Joe Biden wins Democratic presidential primary in Minnesota.
9:49 p.m. WASHINGTON (AP) — Joe Biden wins Democratic presidential primary in Arkansas.
10:27 p.m. WASHINGTON (AP) — Bernie Sanders wins Democratic presidential primary in Utah.
10:48 p.m. WASHINGTON (AP) — Joe Biden wins Democratic presidential primary in Massachusetts, upsetting Elizabeth Warren in her home state.
11:00 p.m. WASHINGTON (AP) — Bernie Sanders wins Democratic presidential primary in California, claiming biggest prize on Super Tuesday.
March 4, 2020
1:57 a.m. WASHINGTON (AP) — Joe Biden wins Democratic presidential primary in Texas, taking Super Tuesday's second biggest prize.
1:57 p.m. WASHINGTON (AP) — Joe Biden wins Democratic presidential primary in Maine.
Follow AP election coverage: https://apnews.com/Election2020