The Arizona county that contains Phoenix added more housing units than all of New York State last year, according to numbers released by the U.S. Census Bureau yesterday.

New York added 33,666 housing units, an increase of 0.4% of its total housing stock, from July 2004 to July 2005. That makes it second-worst among the 50 states in percentage housing growth, trailing only Rhode Island.

In total number of units built, New York ranked 20th. Florida added nearly 247,000 units of housing, followed by California and Texas. States like Minnesota, South Carolina, Georgia, and Wisconsin also beat out New York.

A professor of demographics at Cornell University, Warren Brown, said the state’s tepid pace of housing growth stems from slow population growth, particularly in upstate New York, a trend that he said began regionally in the 1970s.

“There is no increase in population because there aren’t the jobs,” Mr. Brown said. “People aren’t moving here for the climate. They would come for jobs.”

A senior policy analyst at the Regional Plan Association, Alexis Perrotta, said she would not characterize New York’s housing growth as slow.

She said most of the housing growth in states like Florida and Arizona was likely to be single family housing that she said is “barely possible” in most downstate New York areas, which are mostly built out.

“That is plain old suburban growth which is not possible in our region. We already did that. We did that 60 years ago,” Ms. Perrotta said.

A spokesman for the state’s Division of Housing and Community Renewal, Peter Moses, said: “We are very proud of our housing accomplishments in the state of New York. Since 1995, $11 billion has been invested in affordable hosing in this state.”

The Census Bureau also published housing data by county. The fastest growing county by total units was Maricopa County, Ariz., which contains Phoenix. It added 52,000 homes over the period. It was followed by Clark County, Nevada, which contains Las Vegas, and Harris County, Texas, which is home to Houston.

The five counties that make up New York City added more than 16,300 housing units from 2004 to 2005, according to the census. While the city is visibly going through a housing boom, the census figure falls short of the city’s more recent estimates that more than 30,000 units are being constructed.

Still, the number of new housing units reported in New York City is an increase of about 31% over the previous year measured by the census, 2003 to 2004.

A spokesman for the city’s Department of Housing Preservation and Development, Neill Coleman, said the city is sticking by its estimates, which are based on the number of building permits filed each year. He noted that last year more building permits were filed than in any year on record since 1972, and so far in 2006 building permits are being filed at a similar pace.

Mr. Coleman said that there are tens of thousands of housing units now under construction that do not appear in the latest census data but will soon. Mayor Bloomberg has a $7.5 billion plan to build and preserve 165,000 units of affordable housing over ten years.

Mr. Brown, of Cornell, said that the Census Bureau’s methodology underestimates the number of new housing units in New York City. He said the bureau does not take conversions into account, and overestimates the amount of demolitions, or houses lost each year.

“It is probably pretty good data for Flagler County, Florida, but it is probably not good data for the five counties of New York City,” Mr. Brown said.

He said that the Census housing data can have important ramifications. “Some federal monies are distributed to localities on the basis of these estimates, which favors suburban areas,” Mr. Brown said.

An analyst with the Census Bureau, Greg Harper, said that the bureau estimates the amount of housing units destroyed, demolished or inhabitable each year.

“New York City might think we estimate too much loss for them,” Mr. Harper said.

He said that based on the Census Bureau’s building permit data for 2005 to 2006, New York City is due for a substantially bigger increase in new units next year.

An editor of the City Journal, Nicole Gelinas, said that New York State’s tax policy is affecting migration, and is keeping population growth down and stunting housing starts.

“If you look at where all of these houses are being built, it is a story about the migration to the south and the southwest,” Ms. Gelinas said. “All of these places have lower state taxes than New York.”

“People are fleeing high housing costs, but they are also fleeing high taxes and moving to a more hospitable tax climate,” she said.