In a recent post, I suggested that the long-established gap between the wages earned by union workers and those earned by nonunion workers may be narrowing a bit. I also added a parenthetical disclaimer that, when benefits are taken into account, union workers “still typically earn more in terms of total compensation.” The Bureau of Labor Statistics has just released a quarterly report that gives me the chance to fact-check that presumption.

According to BLS’s “Employer Costs for EmployeeCompensation” report for the first quarter, the gap between union and nonunion average hourly compensation—which includes both wages and benefits—widened over the past year. Private-sector employers spent an average $40.43 in hourly total compensation on union-represented employees in the first quarter, compared with $28.02 on nonunion workers.

As expected, benefits accounted for the biggest share of this gap. Employers spent an average $16.27 per hour in benefits (required or voluntary) to union-represented workers in the first quarter. That's more than twice what was spent on nonunion workers ($7.91 per hour). This gap has increased steadily over the years.

In the first quarter, employers spent more than three times as much on union-represented workers than nonunion workers in the following benefits: pensions and other defined benefit retirement plans; short-term disability insurance; overtime and premium pay; and shift differentials.

I was somewhat surprised to see that the gap in wages appears to be widening as well. While not as massive as the 100-plus-percent gulf between union benefits and nonunion benefits, the first-quarter difference between union and nonunion was 20.2 percent, up from 16.1 percent a year earlier. This doesn’t necessarily contradict my earlier post, since the figures I relied on concerned union members in both the public and private sectors.