Sanders supporters
Supporters of Democratic U.S. presidential candidate Bernie Sanders cheer at a campaign rally in San Francisco on June 6, 2016. REUTERS/Elijah Nouvelage

Over the past year, Democratic presidential candidate Bernie Sanders has built a small-dollar fundraising juggernaut unlike anything else in American political history.

In the course of his campaign, he has raised more than $200 million, according to data from the Federal Election Commission. The majority of those contributions arrived in amounts well below $200. As Sanders himself has frequently boasted, the average contribution to his campaign has hovered somewhere around $27.

The perennial underdog has spent more than any other presidential candidate in this cycle — of either party. He's even outspent Democratic front-runner Hillary Clinton by about $25 million, according to the latest election filings.

A large share of the Sanders campaign's expenditures have gone to media and political consultants, as International Business Times previously reported. According to data from the Center for Responsive Politics, the campaign has spent at least $92.4 million on media, with most of that sum going to one firm in particular, the media agency Old Towne Media. Revolution Messaging, a consulting firm led by alumni of Barack Obama's 2008 presidential campaign, has received nearly $24 million from the campaign.

In contrast, Sanders has spent comparatively little to build up his own campaign staff. While Clinton has spent $42.1 million on salaries for her in-house staff, Sanders has invested just $15.1 million. And where the Clinton campaign spent $11.5 million on fundraising expenses, Sanders reports virtually zero expenditures in that category. That may be because his most significant fundraising has been done through consulting firms like Revolution Messaging, which has helped him build his powerful online donor infrastructure.

Such investments have undoubtedly paid off for the Sanders campaign, which repeatedly smashed monthly fundraising records throughout the late winter and early spring. But through the long primary season, Clinton has repeatedly proved to have the stronger ground-level infrastructure when it comes to things like field offices and organizing staff.

As Clinton cemented her lead over Sanders, and every big primary started to look like a life-and-death moment for his campaign, the Vermont senator began spending more and more in the hopes of staging an upset somewhere. Ahead of the New York primary in April, Sanders spent twice as much as Clinton on ads in the state.

Because of such big-ticket expenditures, Sanders has seen his cash reserves shrink heading into the California primary. His campaign started shedding hundreds of employees shortly after New York.

2016 Presidential Candidates Burn Rate | InsideGov

Even given its impressive fundraising list, there might not be much gas left in the Sanders campaign’s engine after Tuesday. But that probably doesn’t matter because the most important number — pledged delegates — says the race is over.