While California wages started the year rising at the nation’s fifth-fastest pace, according to one measure, Southern California pay hikes lag.

The continued modest pay advances — as job growth stays strong with unemployment running at cyclical lows — is a bit of an economic puzzle. Are bosses still penny-pinching with salary or are most workers still too skittish to demand a pay raise? The latest piece of the pay puzzle comes from perhaps the most detailed study of staffing and wage levels.

Every three months, federal job trackers delve into a nation’s worth of unemployment insurance filings. The results are a little tardy — the newest report is for the first quarter — but it’s based on 100-million-plus actual worker files, not a limited survey of bosses or employees. Statewide, this quarterly census shows 17.15 million workers were on the job in 2018’s first three months, up 2.1 percent in a year. Average weekly pay was $1,352, up 4.4 percent — an increase topped only in Washington, Utah, New Hampshire and Nevada.

Southern California workers were not as fortunate. In the four counties covered by the Southern California News Group, a total of 7.52 million were employed in the first quarter, up 2 percent. Weekly wages ran $1,183, up 2.5 percent.

Nationwide, hiring was slower than the local pace but pay rose more. In the first quarter, 144.56 million were working in the U.S., up 1.6 percent. They got an average weekly pay of $1,152, up 3.7 percent.

Among the four local counties:

Los Angeles: 4.42 million workers, up 1.6 percent in a year; paid $1,252 weekly, up 2.3 percent in 12 months — the 243rd biggest pay gain out of the 349 most-populous counties tracked nationally.

Orange: 1.62 million workers, up 2.1 percent. Average weekly pay was $1,258, up 3.2 percent — and 152nd biggest gain nationally.

Riverside: 732,600 workers, up 3.1 percent. Average weekly pay was $890, up 2.8 percent — No. 190 nationally.

San Bernardino: 744,500 workers, up 3.1 percent. Average weekly pay was $902 weekly, up 3 percent — No. 172 nationally.

Some workers have found switching jobs can up pay. A salary index from the Federal Reserve Bank of Atlanta shows the pay of workers who switched jobs rose at an average 3.98 percent annual rate in 2018’s first half. Wages for workers who stayed put rose only at a 2.65 annualized rate in the first half. That’s the largest gap between quitters and loyalists in 18 years.