Understanding who’s coming to California, and who’s leaving, is critical to making critical decisions for policymakers and business leaders alike.

We’ve just seen a state population report showing California had 105,211 more people leave for other states than arrive in the 12 months ended July 1. That net domestic migration was down from 163,922 in the previous 12 months but was the second highest outflow in seven years.

But who are your new neighbors and why did the old ones go? Studies from the folks who help people relocate paint a picture that makes sense for high-cost California: You come for a great financial opportunity; you leave when your income-picture is challenged.

Van line moves are worth watching as a benchmark of the vitality of a state’s economic climate because the folks relocating in professional moving trucks across state lines are typically well-do-to households. My trusty spreadsheet, filled with annual migration data from United, Atlas and Allied van lines, shows 28,144 outbound moves from California in 2017 vs. 24,179 vans coming in.

That net outmigration of 3,965 was the nation’s second-biggest gap between ins and outs behind Illinois. And it was the state’s worst performance since 2006’s 6,673. In both years, just 46 percent of California van moves were inbound.

But what’s behind that imbalance …

No mass exit

Please note the 2017 van-line stats do not signal a growing exodus out of the state.

In fact, mobility in and out of the state by moving van is way down: Last year’s departures — as well as arrivals — are roughly 40 percent below the 2006 levels. It’s part of a growing trend of Americans moving less as the nation’s population ages and relocating gets pricier and less popular.

Plus, incoming California relocations exceeded moves outbound among the three companies in every year from 2008 through 2015. Adding it all up, 365,500 vans came to California in the last 11 years just 1,500 below the departure totals.

California migration patterns on a national basis are best seen through the prism of the state’s comparative size. No state had more outbound van moves than California last year. And no state had more arrivals via van than California as well.

For perspective, I compared the comings and goings of all states to respective tallies of households.

Last year’s exits from California came at a rate of 22 departures per 10,000 households, or 29th out of 48. Best? Arkansas and Vermont. Conversely, vans moved to California at a rate of 19 relocations per 10,000 households — 19th best. Tops was Colorado followed by Washington and Arizona.

Long-term picture

The popularity of individual states as places to live seems to impetuously swing like fashion’s hemlines and lapel widths, who’s in among entertainment’s darlings, or the varying palates of foodies.

One noteworthy benchmark of comings and goings is United Van Lines’ database of 40 years of inbound vs. outbound moves. It shows how states go into and out of favor: Since 1979, 16 different states have been — for at least one year — among the three most desirable while 18 different states have ranked in the bottom three.

Here’s how it’s shifted over the decades …

The ’80s: The good ol’ days for California. By this metric, the state averaged a No. 11 ranking with 53.3 percent of vans headed toward the Golden State as America looked south and westerly.

Florida was tops for the decade, Arizona was next. Then came the Pacific Northwest’s Washington and Oregon followed by Virginia. Colder climates had relatively fewer inbound moves. North Dakota was worst; then West Virginia, Wisconsin, Michigan and New York.

The ’90s: A period of manufacturing retrenchment helped push California down to No. 37, the state’s worst performance of the past four decades as only an average 46 percent of moves involved vans coming into the state.

The most unpopular states included other factory-heavy economies. After North Dakota (the worst) came New York; then the manufacturing hubs of Indiana, Illinois and Pennsylvania. Most popular was Nevada followed by Oregon, Idaho, Arizona then Georgia.

The ’00s: A decade punctuated by the Great Recession saw the South’s popularity rise.

Oh sure, Nevada was the decade’s best, followed by Oregon. But the next inbound leaders were North Carolina and South Carolina. Worst? North Dakota, Michigan, Indiana then New Jersey and Illinois.

California improved only slightly to No. 32 at 48.3 percent inbound.

The ’10s: In the past eight years, California has regained some momentum.

It’s back with more move-ins than outs, averaging 51.6 percent arrivals since 2010 and ranking No. 16 among the states. By the way, the Golden State enjoys the current decade’s seventh-best improvement in this gauge of geographic desirability vs. the 2000s.

Not much changed at the top of the overall rankings for the ’10s, only the order: Oregon’s No. 1 followed by South Carolina and North Carolina. Worst had familiar names, too: New Jersey, Illinois, New York and Connecticut … with a new state in a state of dislike: Kansas!

Who’s moving?

California often lures the younger and well-paid, while those departing are frequently seeking a spot for their golden years.

That’s according to new demographic research done by United Van Lines, which handled 23,779 moves in and out of California in 2017.

Start with employment. The top relocation motivation for 65 percent of households arriving by van said they came to California for jobs. Only 43 percent of those departing by moving van described the move was work-related.

The jobs rush means your new neighbors are likely wealthier than the people they replaced. United’s study showed 68 percent of arriving households make $100,000 or more annually; just 63 percent of those departing by moving van make above that threshold.

Retirement is a factor: Only 10 percent of relocations to California by United van was part of a retirement plan while 21 percent of those leaving the state said the departure was for a new, post-work life.

So these newbies are younger. Just 35 percent of those coming to California by moving van was under age 55 vs. 51 percent of those leaving.

The do-it-yourselfers

Trends in U-Haul’s do-it-yourself moves can be seen as a benchmark of popularity for shifting households with relatively modest incomes.

U-Haul, which doesn’t disclose the number of moves it handles, said 49.6 percent of its California interstate trips last year were folks driving to the state.

California’s lean toward departures was the result of arrivals growing by 4 percent vs. 2016 while exiting trips surged by 5 percent. That helped give California the worst score in its “growth states” ranking. Texas, Florida, Arkansas, South Carolina and Tennessee were the top five.

That’s the second-straight year California scored poorly. The state ranked next-to-last for “growth” in 2016. Arrivals fell by 1.2 percent as exits ran flat. But in 2015, California was U-Haul’s No. 5 “growth state.” A 3.2 percent jump in inbound trips outpaced unchanged departures.

U-Haul’s ranking shows its negative statewide trends aren’t universal. Four California cities made U-Haul’s Top 25 “growth cities” list for 2017: Sacramento ranked sixth best in the nation; No. 13 was Redding; No. 17 San Francisco; and No. 23 Murrieta.