Two of the leadin g voices on this question are Charles Varner, a sociology graduate student at Princeton University and Cristobal Young, a sociologist at Stanford University. In the last few years, the two have published studies on the relationship between tax increases on high earners and the migration of wealthy people from two states: New Jersey and California [PDFs].

In 2004, New Jersey raised the marginal tax rate on income above half a million dollars a year by 2.6 percent – more than five times de Blasio’s proposed New York City hike. The tax hike had little effect on the migration of millionaires out of the state. The authors found only the slightest increase in out-migration for millionaires under the new tax policy, just 5.2 households per thousand. The number of millionaires, and by extension the base for this newly heightened tax rate, was determined far more by year-to-year changes in state residents’ income than by people moving to flee unfavorable tax situations.

The biggest predictor of whether a millionaire will move is divorce.

In California, the pair found similar results when looking at the effects of two policy changes that occurred between 1994 to 2007: a 1996 tax cut for high-income residents, and the introduction of a 2005 “millionaire tax” of 1 percent on taxable income greater than $1 million. For the tax cuts enacted in 1996, the authors found essentially no clear pattern of increased in-migration of wealthy residents from nearby states looking for better tax situations. Changes in income accounted for nearly 90 percent of the year-to-year shifts in the number of wealthy residents. As for the 2005 millionaire tax, they found that there was essentially no effect – just “zero-plus-noise.” (In fact, across the board, the biggest predictor of a millionaire’s decision to leave the state was whether he or she got divorced.) Their conclusion: “Migration is a very small component of changes in the number of millionaires in California.”

The basic fact is that it is not taxes but other, more compelling and substantial factors that are drawing more and more high-skilled, productive and, yes, rich people to places like New York City, Los Angeles, the Silicon Valley and San Francisco. As University of Michigan economist David Albouy has noted, these places offer a powerful combination of enhanced productivity and greater “quality-of-life” amenities. He looked at housing and land value, along with data on trade productivity and quality-of-life measures and found that diverse, vibrant, and interconnected cities like San Francisco, New York, Los Angeles, and San Diego are the most “valuable” large metros.

The knowledge economy boom is propelling this trend forward. My own research and that of others document the trend of higher skilled, more affluent people and even high-tech companies and talent flocking back to urban centers. A recent study of the location choices of “ultra high net worth” individuals (those with a net worth of $30 million or more) found that between 2012 and 2013 their ranks increased by 4.1 percent in New York State, 14.7 percent in California, and 35.2 percent in Massachusetts, a state conservatives like to dub “Taxachussets.”