The former secretary of state was the victim of a system that awards electoral college votes mostly on a state-by-state basis. So she lost despite winning some 400,000 more popular votes than her adversary, according to preliminary results published by American media.
That number may be a drop of water when compared to the 130 million ballots cast in the presidential election Tuesday, but it gives Clinton and her Democratic backers bragging rights, even as it fans a sense of injustice: Some 60.4 million voters chose her, to 60 million who preferred her Republican rival Trump.
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Thus, if the election were based on direct suffrage, the former first lady would now be president-elect, winning by a 48 per cent to 47 per cent margin.
Under the US system, each state has a number of electors based on its congressional representation - which in turn depends on its population. So a big state like California has 55 electors, while a small one like New Hampshire has four.
Election to the presidency requires support from at least 270 electors, a simple majority of the 538 at play. The electors, mostly party activists, cast their ballots on December 19 - normally a simple formality.
The battleground factor
But the system can twist the popular will.
Because a state like California is so predictably Democratic - just as a state like Kansas is so predictably Republican - the fight mostly comes down to a handful of so-called battleground states that can swing either way and decide the outcome.
And Trump managed to win most of those key states - like Florida, Ohio and Pennsylvania - assuring himself of at least 290 electors to Clinton's 228, easily surpassing the 270 needed.
This raises "the question of how democratic our system is," noted Robert Shapiro, a political science professor at Columbia University in New York.
The "one person, one vote" rule, considered a pillar of democracy, does not square with a system of indirect suffrage, he said.
The system seems "to really fly in the face of this central principle of political equality," Douglas McAdam, a sociology professor at Stanford University in California, said Saturday on CNN.
Calls for electoral defiance
Rejecting this approach, a petition launched on the Change.org website and signed, as of Saturday, by nearly 3.5 million people, demands that the electoral college, when casting its votes on December 19, select not Trump but Clinton.
Technically, that is possible.
But in reality, the demand has little chance of succeeding, because electors are chosen precisely for their faithfulness to their party. Only a handful through US history have gone against the will of their states' voters.
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Backers of the Change.org petition, who see Trump as "unfit" to govern, say that electors from states where he won the popular vote could still cast a vote for Clinton, though they might face a "small fine" for doing so.
As a candidate, Trump himself often denounced the electoral system as "rigged" and threatened that he might not respect its result.
He has not uttered such criticism since his victory Tuesday.
Clinton, for her part, has conceded, and asked her followers to respect Tuesday's outcome. She seems unlikely to support an electoral college rebellion.
'Upstanding citizens'
McAdam said the US system, rooted in the Constitution, originally aimed at electing "really upstanding citizens who themselves would decide who the president was going to be," an idea meant to address fears that poorly educated voters might be swayed by dangerous and alluring demagogues.
"In an electoral college system, every vote certainly doesn't count equally," McAdam said.
"The votes that happen to be cast in battleground states, the half a dozen states that decide elections, clearly count much more than votes" in reliably Republican or Democratic states.
Any modification of the electoral college would require amending the sacrosanct US Constitution, a long and delicate task, according to Shapiro.
Supporters of the current system say that if an election was extremely close, the resulting recount across all 50 states would be a nightmare - witness the agonisingly long recount in a single state, Florida, in 2000.
Specter of national recounts
For McAdam, however, such recounts - even if needed in several states - would not be that difficult, "given modern technology."
Without amending the Constitution, individual states could adopt laws requiring electors to vote for the candidate who received the most popular votes nationwide.
But such ideas have made little headway.
Rob Richie, whose FairVote group advocates for several reforms of the system, has suggested changes both in the electoral college and the primary election systems.
He also suggests lowering the voting age from 18 to 17, in a country where voter participation has been notably low.
Only 56.9 per cent of eligible Americans voted on Tuesday, according to Michael McDonald, a University of Florida professor who specialises in elections.
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