This morning, we have a New York Times/Siena College poll in a place that might surprise you: New York City.

Overall, Kamala Harris leads Donald J. Trump, 66 percent to 27 percent. Although it’s a significant advantage, it also represents a major decline in Democratic support since 2020, when President Biden won the city, 76-23.

If it held, it would represent the worst showing for a Democratic presidential candidate in the city since 1988.

New York City does not figure prominently in the electoral calculus of either campaign, but it may nonetheless be an important part of the story of this election.

A strong Trump showing in the city would offer important clues about what’s propelling his gains nationwide. The poll adds to the evidence that his gains are concentrated in the places where Republicans fared well in the midterm elections, suggesting that the pandemic and the upheaval in its wake left a lasting mark on the electoral map — and may blunt Mr. Trump’s advantage in the Electoral College.

As we’ve reported all cycle, Mr. Trump has made important gains among Black, Hispanic and younger voters, but it increasingly seems his gains will vary greatly from state to state or even city to city. Our recent poll of nearby Philadelphia, for instance, showed Ms. Harris doing just fine there (79-16).