At stake is more than simply bragging rights: Next year’s decennial census, which is supposed to count everyone in the country, will determine the size of the New York congressional delegation and the distribution of billions of dollars in federal aid. The city is projected to lose two seats in the House of Representatives after the 2020 count.

The estimated decline, to 8,398,748 from a record 8,438,271 in 2017, covers the year ending on July 1, 2018. It amounts to 39,523 New Yorkers, or fewer than live in Co-op City in the Bronx.

The loss breaks down to 18,000 in Queens, 13,500 in Brooklyn, 7,500 in the Bronx and 1,000 in Manhattan. Staten Island recorded a gain of 663.

The latest figures suggest that population shifts in New York reverted to what had been a conventional pattern: Typically, more New Yorkers move to other parts of the United States than come from elsewhere in the country. But immigration from abroad usually makes up that loss, and tends to push the city’s population higher.

This time, 137,000 more New Yorkers left the city for other parts of the country — retiring or moving to less expensive cities in the Sun Belt — than arrived from someplace else in the United States. The net increase in international migration was only about 49,000.