Workers at Long Island companies had slightly bigger pay checks last year, but the wage growth here was uneven and remained below the state’s and the nation’s, U.S. Bureau of Labor Statistics data released this week show.

Average weekly wages climbed 2.3 percent in Nassau and just 1.4 percent in Suffolk in the second quarter of 2015, from the same period in 2014. And both counties fell below the state’s 3.1 percent and the nation’s 3 percent growth in weekly pay. The data from the spring are the latest available.

Wages in Manhattan, or New York County, grew 3.3 percent year-over-year.

John A. Rizzo, chief economist of the Long Island Association, said that some demographic factors might be holding down wages here, despite strong job growth.

He speculated that more baby boomers at the peak of their earning power are retiring and are being replaced by younger workers earning less. And he also believes the weak pay increases may indicate that more young professionals are opting to live and work off Long Island because of the lack of affordable housing here.

Bruce Bergman, an economist in the BLS’ Manhattan office, said that Suffolk suffered in part from slow wage growth in manufacturing, a higher-paying sector that accounts for about 10 percent of that county’s private-sector jobs, three times the percentage for Nassau.

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Manufacturing wages in Suffolk declined 2.2 percent in the second quarter from a year earlier, compared with a 1.3 percent rise in Nassau.

Manufacturing in general has been one of the Island’s weakest labor market performers. In December the sector had 71,600 jobs, down 300 from a year earlier, state Labor Department data show.

Meanwhile, in the Island’s highest-paying category, financial activities, wages rose just 1.2 percent in Nassau but jumped 7.9 percent in Suffolk in the second quarter of 2015, compared with a year earlier.

During that time Nassau lost about 190 finance jobs while Suffolk gained 140, said Shital Patel, labor-market analyst in the state Labor Department’s Hicksville office.

“Part of the reason is due to the consolidation of the finance industry and the loss of those jobs in Nassau County, while lower-paying jobs, particularly in retail and accommodation and food services, have been gaining,” Patel said.

More recent data from the state Labor Department showed losses for the financial sector overall. It had 71,100 jobs in December, down 300 from the year before.

Meanwhile, second-quarter wage growth in the leisure and hospitality sector, which includes accommodation and food services, was relatively strong in both counties — up 3.2 percent in Nassau and 3 percent in Suffolk.

Overall, Nassau’s average weekly wage rose to $1,094, compared with $1,025 in Suffolk. The state’s was $1,180 and the nation’s $968. Manhattan averaged $1,842 a week.

The BLS wage data include public and private-sector jobs and bonuses. They are based on wage information from companies covered by the unemployment-insurance program, which includes about 98 percent of employers.