The Los Angeles Daily News wrote an interesting article evaluating Census Bureau migration data for 2018 as it applies to California's population trends. The article shared stats regarding out-flow: 691,145 Californians left the state last year. It also evaluated California's in-flow: 501,023 arrived from other states in 2018.
Our key takeway was one important statistic included in the piece: 497 Californians come to Idaho for every 100 that leave Idaho to go to California.
You can read the article in its entirety, here.