NEW YORK -- For all its crowds, Manhattan also has the highest percentage of single- person households of any county in the nation, according to the US Census Bureau.
''I think it's the best way to live," said James Conaboy, 35, a musician who, after years of living with roommates, spent a morning this week hunting for a small apartment in Manhattan's East Village. ''If you want to make a mess, you can make a mess. If you want to paint the walls a certain color, you can do it."
Privacy, he explained, has special value in New York, where people spend their days surrounded by people. Living alone in a rural setting wouldn't be as appealing to him.
''Then you turn into the Unabomber," Conaboy said.
Attracted by a dizzying social scene and studio apartments, some 354,336 people were living alone in Manhattan at the time of the 2000 Census. An analysis of the data was published this month.
Solos accounted for 48 percent of all households on the island, putting Manhattan ahead of other singles magnets like Washington, D.C., St. Louis, Denver, and San Francisco.
And overall, the report said, the number of Americans living alone has exceeded the number of households composed of the classic nuclear family: a married couple and their biological children.
Thomas F. Coleman, executive director of Unmarried America, an association that promotes the political interests of single people, credits part of the shift to changing social norms.
People living alone, especially unmarried women, used to be viewed with sadness, he said.
''Self-esteem isn't based on having children and being married anymore," Coleman said.
Economics also probably plays a role, says Gordon F. De Jong, a professor of sociology and demography at Pennsylvania State University's Population Research Institute.
More people are going to college, he said, meaning that they eventually get higher-paying jobs that allow them to live by themselves. Older people today have better assets, meaning they can more easily afford to live in their own homes after a spouse dies.
Among the Manhattanites living alone, a slim majority, 56 percent, were women. About 23 percent were people older than 65.
''I think, in some ways, the city is a wonderful place to be old and alone," said Marcia Stein, executive director of Citymeals-on-Wheels, which delivers food to 17,000 senior citizens in New York every day.
On a nice day, elderly people can easily leave their homes and sit in the park, walk to the bank on the corner, or go to a museum or to the neighborhood coffee shop, she said.
''They have neighbors on the same floor of their apartment building, or across the street who they probably see every day," she said. ''When an older person lives in a rural area, or a suburban area, they have to be able to drive a car. Our people don't need to do that."
The analysis found that the number of single-person households in the United States grew 21 percent in the 1990s, eclipsing the growth rates for all other types of living arrangements.
About 27.2 million Americans lived alone in 2000, accounting for about 26 percent of all households and about 9.7 percent of the overall US population.
By comparison, 22 percent of households consisted of a married couple and their biological children. About 21 percent were married couples living alone. Eight percent were single parents living with at least one child.
Other combinations -- including multigenerational households, unmarried partners, people living with their extended families, grandparents raising grandchildren, and 24,722 other recorded types of arrangement -- were less common.
The increase in the percentage of single-person households is a continuation of a trend that began decades ago. In 1950, just 9.3 percent of US households consisted of people living alone, according to the Census Bureau.