Texas is the biggest recipient of that outflow.

The Washington Times reports that a recent analysis found that the numbers of California residents fleeing the state are "unprecedented" and that Texas is the greatest destination by far:

About 5 million Californians departed the Golden State between 2004 and 2013, while 3.9 million arrived from other states for a net population loss of roughly 1.1 million...

That amounts to an estimated loss in tax revenue of about $26 billion annually, according to an analysis by the Sacramento Bee.

Using tax return data from the Internal Revenue Service, the analysis found that about 600,000 former California residents made their way to Texas, while about 348,000 Texas residents moved to California. Other top recipients of former California residents included Arizona, Nevada, Oregon and Washington.

California's population has nonetheless increased – from 37 million in 2010 to 39 million today – but that is primarily due to an massive influx of foreign-born immigrants, many of whom are in the country illegally and are net recipients of government aid rather than contributors. Overall, the analysis showed, people who leave California earn more than those who enter the state.