See the results from every 2020 Democratic presidential primary state so far

• The Democratic primary election process continues tomorrow in Ohio, Arizona, Illinois, and Florida, where former Vice President Joe Biden is expected to expand his sizeable lead over Sen. Bernie Sanders.
• According to estimates from Decision Desk HQ in partnership with the University of Virginia Center for Politics, Biden has earned 866 pledged delegates while Sanders was won 709.
• Here's a state-by-state breakdown of how many delegates each candidate has won in every primary contest so far.
• Visit Business Insider's homepage for more stories.

The Democratic primary election process continues tomorrow with primaries in Ohio, Arizona, Illinois, and Florida, where former Vice President Joe Biden is expected to expand his sizeable lead over Sen. Bernie Sanders.

The Democratic nomination isn't decided by who wins the most votes but by which candidates receive the most delegates - people selected by each campaign from every state or district - to represent them at the Democratic National Convention, taking place July 13-16 in Milwaukee.

According to estimates from Decision Desk HQ in partnership with the University of Virginia Center for Politics, Biden has earned 866 pledged delegates while Sanders was won 709.

Every state has a certain number of delegates to allocate, which is determined by numerous factors including how big the state is, how Democratic it leans, when it votes, and whether it votes with its neighbors.

Democrats allocate most of their pledged delegates proportionally by legislative district, in addition to allocating at-large and PLEO (party leader and elected official) delegates based on the statewide vote breakdown.

Most states allocate their delegates by congressional districts, but some, like Texas and New Jersey, use state legislative districts instead.

While delegates are allocated proportionally, in nearly every state the minimum threshold to earn delegates is 15% of the vote. This means candidates must break 15% of the vote either at the district or state level to earn any delegates at all.

With such a crowded 2020 field, candidates inevitably fail to meet the delegate targets or drop out altogether.

Former Mayor Pete Buttigieg of South Bend, Indiana, Sen. Amy Klobuchar of Minnesota, Sen. Elizabeth Warren, and former Mayor Mike Bloomberg suspended their campaigns after earning a combined 141 pledged delegates.

When candidates drop out, the delegate slots they have earned - which are filled by real people - can be told either to support a rival candidate or to be released to vote for whomever. In many states, state-level delegate slots earned by candidates who later drop out are automatically re-allocated to the next-highest performing candidate.

Not all the states that have voted so far have, however, have fully reported all their results, meaning some delegate projections are incomplete with delegates left to be allocated from some states.

Washington, for example, conducts its elections entirely by mail and almost a week after its primary, has only reported about 50% of its results. And California, which held its primary almost two weeks ago on Super Tuesday, is still fully counting all mail-in and provisional ballots.

Here's a state-by-state breakdown of how many delegates each candidate has won in every primary contest so far, from the very beginning of the primaries: