Finally, there are the millions of eligible voters who are their own worst enemies. They may be unhappy with the choices before them or unconvinced that their votes will make a difference. Either way, they sit out Election Day, nursing their grudges and telling themselves that they’re making a political statement. Wrong.

Whether or not the cynics believe it, every vote really can make a difference. An election in 2017 for a legislative seat in Newport News, Va. — a seat that happened to determine control of the state’s House of Delegates — was effectively decided by a single vote, out of more than 23,000 cast.

Or take an even more consequential example: In the 2014 midterm elections, barely more than one in three eligible voters turned out; 143 million others stayed home. It was the worst showing in 70 years, and one of the weakest midterm turnouts in United States history. The only people celebrating were Republicans, because smaller electorates tend to be more conservative ones. The abysmal turnout in 2014 followed that pattern, and it allowed Republicans to seize control of the Senate. That gave Mitch McConnell, the majority leader, the power to shift the Supreme Court to the hard right for at least a generation.

Still think voting doesn’t matter?

This message is especially important for young people like Mr. Hagezom, who lean strongly Democratic and yet are notoriously bad about showing up to the polls. In 2014, the turnout rate for voters under age 30 was less than 20 percent. This year’s numbers, so far, are looking much better, and they will very likely remain high in 2020, when President Trump will be on the ballot. But beyond that, the struggle to keep young voters politically engaged will continue.

No matter who wins, higher turnout is a good thing. It reaffirms the essence of the democratic process, and it tends to help candidates who are both more reasonable and more representative of the public at large.

It’s also true that when more people vote, the electorate becomes more liberal. If Americans voted in proportion to their actual numbers, a majority would most likely support a vision for the country far different from that of Mr. Trump and the Republicans in Congress. This includes broader access to health care, higher taxes on the wealthy, more aggressive action against climate change and more racial equality in the criminal justice system.

Republicans are aware of this, which is why the party has gone to such lengths to drive down turnout among Democratic-leaning groups. A recent example: In North Dakota, the Republican-led Legislature changed the law to make it harder for Native Americans to cast a ballot.

It comes down to this: Democracy isn’t self-activating. It depends on citizens getting involved and making themselves heard. So if you haven’t yet cast a ballot, get out and do it on Tuesday, or earlier if your state allows early voting. Help your family, friends and neighbors do the same. Help a stranger. Vote as if the future of the country depends on it. Because it does.

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