The final days of US elections are typically devoted to huge drives by each side to produce voters on Election Day. That’s true this year, but with important caveats: The efforts are far more sophisticated, and more than one-third of the electorate, or more than 40 million voters, will have voted by the time the polls open Nov. 8.

Registration and early voting trends may provide as many clues as polls and messaging. They indicate an advantage for Hillary Clinton.

This advantage will turn into an avalanche if Donald Trump can’t recover from his latest self-induced crisis: an 11-year-old video in which he can be heard boasting of his sexual prowess and making graphic and vulgar remarks about women.

Early voting is closely tracked by the US Election Project, directed by Michael McDonald, a University of Florida political scientist. He estimates that 34 percent of the electorate will vote before Nov. 8, up a little from four years ago.

To date, there are three states where a preliminary reading is possible and can be compared to this period four years ago, McDonald says. Republicans are doing a little better in Iowa; the picture is mixed in Maine; and Democrats have reason to cheer about North Carolina, a critical battleground. (According to a law enacted in 1845, no ballots can be counted until Election Day.)

In a number of states, including North Carolina, Republicans have sought to crack down on early voting, claiming such measures were necessary to prevent fraud. The courts, however, have thrown out some of these laws, finding they tended to suppress black votes. Some restrictions remain.

Both parties crow about successes in registration. Republicans cite pickups in Pennsylvania; the other side points out that Colorado has more registered Democrats than Republicans, for the first time in decades.

Dave Wasserman, an election expert at the Cook Political Report, says Republicans have lost an opportunity. In 2012, there were 47 million noncollege-educated whites, more than half of them men, who didn’t vote. This is a constituency where Donald Trump does well.

But, Wasserman notes, “There are no indications they are registering for Trump in any real numbers.”

Instead, he finds that new registrants in counties where the population has higher education levels and that are more racially diverse — places where Clinton can be expected to do better — are coming in at a higher rate.

Finally, there’s the question of identifying and turning out voters. After the 2012 election, the Republican National Committee conducted an autopsy that concluded the party had to emulate President Obama’s turnout model.

As with other recommendations — immigration reform, outreach to minorities — the follow-through fell short.

“The evidence we have is there is a big gap on resources and planning between the two sides, favoring Clinton,” says Sasha Issenberg, author of “The Victory Lab: the Secret Science of Winning Campaigns,” and a consultant to Bloomberg Politics.

A glance at current polls underscores the importance of turnout. In Ohio, several surveys have shown Trump clearly ahead.

One reason is a significant drop-off of the black vote, which comprised 15 percent of the total last time. If that persists, Trump likely will win Ohio. If the Clinton campaign can replicate the 2012 turnout — helped by basketball star LeBron James’ endorsement of the Democratic candidate last week — the odds change.

The same is true in states such as North Carolina. The biggest challenge for Clinton may be young voters, many of whom can’t stand Trump but aren’t turned on by his opponent.

Issenberg suspects the Democrats’ superior voter turnout infrastructure will continue to outperform. He ventures that in a key state where the polls showed each candidate getting 45 percent on election eve, “Clinton is best positioned to turn that into 47 percent, while Donald Trump would end up at 44 percent.”

With Trump’s latest debacle, he may not do that well in many states.

Albert Hunt is a Bloomberg View columnist.