According to a Manhattan Institute study called The Great California Exodus: A Closer Look, 4.2 million Americans moved to California from other states between 1960 and 1990.
Since 1990, however, the state has lost nearly 3.4 million residents through migration to other states, like Texas, Nevada, Arizona, Oregon, Washington, Colorado, Idaho, Utah, Georgia and South Carolina. The average number of residents leaving the state each year over the last decade is 225,000, the report found.