The Bee website has a nice interactive map with pop-up info for each state.
The Sacramento Bee examined IRS records to determine that roughly five million people left California for other states between 2004 and 2013, the height of the recession and housing bust. Another 3.9 million people came here from other states, for a net population loss of more than 1 million people via domestic migration. But the state's population went up due to births and foreign immigration, the Bee says.
The analysis is based on the information on federal tax returns and requires some interpolation based on the number of dependents that taxpayers claimed. But IRS data is considered a more accurate take on who comes and goes than other sources, which are often estimates. From the story:
An unprecedented number of Californians left for other states during the last decade, according to new tax return data from the Internal Revenue Service….
The trend resulted in a net loss of about $26 billion in annual income.
About 600,000 California residents left for Texas, which drew more Californians than any other state. Roughly 350,000 people came from Texas to California.
The recession and housing bust, which hit California harder than most states, likely played a role in the trend. Conservative analyst and Hoover Institute Fellow Carson Bruno also blames the state's high cost of living and tax structure.
Based on tax returns, the IRS migration data is considered the gold standard for measuring population shifts, though it lags two to three years behind the current date. The latest, separate estimates from the state Department of Finance showed net domestic migration losses slowing, but not abating, in 2014.
Check out the interactive map on the Bee site with pop-up information on each state. The states that have the most exchange with California are typically the states that border us plus Texas, which has just has a much bigger population and economy than our neighbors.