In 2020-2021, there was a rapid decline in the population of major urban areas such as San Francisco and Manhattan — an unprecedentedly rapid decline. Usually, cities don’t lose more than 1% of their population in a single year. But Manhattan lost 6.6% of its population from July 2020 to July 2021, while San Francisco lost 6.3% of its people.
Detroit was the most rapidly shrinking major U.S. city between 2000 and 2020, and even it shrank by more than 1% annually in only about half the years between 2000 and 2020. But in 2020-2021, a great many cities lost more people than that. Prosperous cities like Washington, DC, Boston, and Alexandria lost 3% of their people in a single year.
From July 2020 to July 2021, San Francisco’s population decreased by an estimated 6.3%, losing nearly 55,000 people in that time frame. San Mateo County was fourth, with its population decreasing 3.2% and a loss of nearly 25,000 people.
Domestic out-migration, or the movement of people out of the counties and elsewhere in the U.S., drove population loss from all the fastest-shrinking counties. Domestic out-migration from San Francisco was more than 10 times larger from July 2020 to July 2021 than over the previous year, and nearly nine times higher in San Mateo County.