But a study by Professor Massey and two colleagues, published in September, estimated that the previous tax increase cost New Jersey only 50 to 350 existing “half-millionaire” households  a relatively small number against the total of 44,000 such households in the state.

While those departures cost the state about $38 million a year in revenue, the study estimates, the higher taxes levied on those who stayed have brought in an average of $895 million a year. Also in 2004, California voters approved a 1 percent income tax surcharge on personal income over $1 million, and Silicon Valley and Beverly Hills appear to remain well populated with the wealthy. From 2004 to 2007, according to a study by the California Budget Project, a left-leaning research organization, the number of millionaire taxpayers rose by close to 50 percent, well outpacing the 8.6 percent growth in the total number of those paying personal income tax.

“It is one of the oft-cited urban legends in California politics  that the rich are leaving California because of higher taxes,” said Jean M. Ross, the project’s executive director.

Between 2003 and 2005, after the Sept. 11 attacks, New York State imposed a temporary surcharge on incomes of more than $100,000, as did New York City. While the city did lose residents at all income levels in 2005, according to a 2007 study of population data published by the city comptroller, William C. Thompson Jr., households with incomes of $250,000 and higher were the least likely to leave.

Some who study the issue theorize that other factors affecting people’s decisions about moving  schools, jobs, even the weather  make it unlikely that a relatively small tax increase would drive those decisions. In states like New York and California, hubs of culture and specific industries, people may also stay out of a desire to live and work near others like themselves.

“People move to maximize their utility,” Professor Massey said. “The $64,000 question is, what is their utility? There are taxes and income, but there are issues about jobs, local amenities in the state, family.”

Some research suggests that very wealthy retirees will move when their home states raise income taxes or preserve estate taxes, though in small numbers. And studies counting the number of wealthy taxpayers who stick around may not, of course, capture those who choose not to move to a state because of higher taxes.