After a time of few if any raises, the demand for labor has risen enough to compel some employers to pay more to hire or retain workers.

The gains are modest, but they should slowly accelerate as unemployment falls further and competition for quality workers increases. Wage gains are now at about 3 percent compared with 2.2 percent previously.

The United States Bureau of Labor Statistics reports that gains are the strongest in construction with a 3.8 percent increase. The wages of professional and business-service workers have risen by 3 percent.

There are now just 1.5 unemployed job seekers for every opening, down from 6.8 in 2009. Economists say that U.S. and global economic fundaments should lead to higher wages.

The Labor Department’s gauge of average hourly earnings for all jobs in all categories recently posted a 2.5 percent gain.

But Chicago-based staffing company LaSalle Network tells Bloomberg Businessweek that they see increases in specific positions and specific areas, not increases across the board. Economists calculate that a robust increase in labor productivity is a missing factor. Gains in productivity, the dollar value of goods and services a worker produces in one hour, have averaged 1.3 percent since 2007.

Roberto Perli, a partner at Cornerstone Macro, a research firm, says that in spite of this, wages seem poised to accelerate.