The 2020 census started Tuesday in a remote Alaskan village where the Census Bureau’s director personally enumerated one of the town’s oldest residents.

This year’s decennial count will be the first one conducted primarily online. Most Americans won’t get a mailer asking them to respond until the middle of March. But in Alaska, a door-to-door response operation always gets under way first so census takers can reach far-flung houses that lack addresses and internet access while the ground is frozen and easier to traverse.

This year that effort started in Toksook Bay, a snow-covered enclave of about 659 people perched on the Bering Sea. The Wall Street Journal in November wrote about how residents wrestled with which Alaskan native inhabitant would get the honor of being the first American counted in 2020.

The distinction went to Lizzie Chimiugak, who recently celebrated her 90th birthday (though her exact age is a matter of debate). Census Bureau Director Steven Dillingham flew into the village Tuesday and knocked on her door, said Katie Schwartz, one of Ms. Chimiugak’s daughters.

With temperatures hovering in the midteens, Mr. Dillingham arrived layered in cold-weather gear, including a thermal coat he bought specially for the trip. He brought paper and a pencil to take down Ms. Chimiugak’s answers to the nine questions on the 2020 form.