Business could get even busier soon. The Republican tax plan aims to encourage business investment by cutting corporate taxes, which could increase demand for the big projects — hospitals, airports, office building — that make up a big part of McCarthy’s business. In fact, Mr. Bolen said, many clients are already making plans on the assumption that the legislation will pass.

“A lot of people are making decisions this year assuming that it’s going to happen,” Mr. Bolen said. “If it doesn’t happen, I think you’ll see some people pull back.”

The challenge for McCarthy, as for other builders, is finding the workers for their projects. A couple of years ago, Mr. Bolen said, job seekers would line up outside the gates of construction sites, hoping for a chance to work. Today, McCarthy is having so much trouble finding qualified workers that it is building a 10-acre training center outside of Houston and hiring staff members to teach construction skills.

“It’s a really big deal now, probably a bigger deal than I’ve ever seen it, and I don’t see it getting better,” Mr. Bolen said. “We are spending a lot of money and effort trying to train up the unskilled portion of our work force.”

The question vexing many economists is why, if labor is as scarce as Mr. Bolen and other executives claim, workers are not seeing bigger increases in their paychecks. McCarthy has raised pay, especially for people with specialized skills. But over all, wage growth remains restrained. Average hourly earnings were up 2.5 percent in November from a year earlier, only a bit faster than the rate of inflation.

“It’s still just creeping higher,” said Brett Ryan, an economist at Deutsche Bank in New York. “Wage growth is just not taking off the way we’ve seen in the past.”

That picture could change. Other measures of earnings, for example, show faster growth. And according to an analysis by Ian Shepherdson, chief economist for the forecasting firm Pantheon Macroeconomics, wages are rising faster in regions where the unemployment rate is lowest. That suggests that pay growth could accelerate if the unemployment rate continues to fall in 2018 as Mr. Shepherdson expects.