French tourists didn’t believe the young guy on the subway was New York City’s new mayor, so he held up the newspaper to prove it

Less than 24 hours after throngs of ecstatic supporters poured into Manhattan for his history-making inauguration, Zohran Mamdani began his first full day of work with a routine familiar to many New Yorkers: trudging to the subway from a cramped apartment.

Bundled against the frigid temperature and seemingly fighting off a cold, he set out Friday morning from the one-bedroom apartment in Queens that he shares with his wife. But unlike most commuters, Mamdani’s trip was documented by a photo and video crew...