Construction backlog fell by 4 percent during the last quarter of 2016, according to the latest Construction Backlog Indicator (CBI) released by Associated Builders and Contractors (ABC).

Contractors in each segment surveyed—commercial/institutional, infrastructure and heavy industrial—all saw lower backlog during the fourth quarter, with firms in the heavy industrial segment experiencing the largest drop. Overall, backlog—the amount of work under contract but yet to be performed—fell to 8.3 months during the fourth quarter. CBI rose a modest 0.4 months or 4.5 percent on a year-over-year basis.

“Many factors contributed to the dip in contractors’ backlog, but none is more important than the lack of public construction spending momentum,” says ABC chief economist Anirban Basu. “Indeed, backlog among firms specializing in infrastructure has declined from 12.2 months during the final three months of 2015 to 10.6 months one year later.

He says that the CBI is a predictive tool and has accurately predicted declining public spending for several quarters, adding that recent construction spending data confirm these declines.

“A still fragile global economy, strong U.S. dollar, and stubbornly low energy prices have helped to translate into declining heavy industrial backlog,” he says. “The only category experiencing construction spending stability is the commercial segment. Over the past year, construction spending in office, lodging and similar categories has surged. During that same period, the CBI reading in the commercial/institutional category has remained stable.”

Backlog declined in all major regions of the nation during 2016’s final quarter except the Northeast. A surge in financial activity and foreign investment in commercial real estate helped buoy construction in the New York metropolitan area, according to available CBI survey data. Boston continues to be propelled by its large and expanding technology sector, and stable economies in both Washington and Baltimore have also helped to drive Northeast CBI higher.

The Middle States region’s backlog sits at approximately 7.8 months. Though this represents a decline on a quarterly basis, backlog is still more than a month higher than it was a year ago.

Backlog in the West declined during the fourth quarter and is now at its lowest level since the first quarter of 2015. The region’s backlog has now fallen in four of the previous five quarters, largely due to dynamics among large construction firms. The technology boom in many communities, including in Silicon Valley and Seattle, has led to massive construction projects in recent years.

Backlog in the South fell during 2016’s final quarter, ending a prolonged period of growth that began during the third quarter of 2015. Despite this setback, backlog in the southern region remains elevated due to the volume of construction in several of the region’s most economically dynamic major metropolitan areas, including Dallas, Atlanta, Orlando and Miami.