New York City is using ranked choice voting in its Democratic mayoral primary election Tuesday, a system that takes some explaining, even for New Yorkers who have used it before.

Millions of New York City voters are heading to the polls to pick the Democratic nominee in November's general mayoral election. NBC News’ Vaughn Hillyard reports on the frontrunners and details how a ranked choice election works.

As a sweltering Primary Day turned to evening, candidates made last-ditch efforts to turn out voters. Andrew Cuomo and Zohran Mamdani are locked in a tight contest. Polls close at 9 p.m.