The number of construction projects under way nationwide shows a slight uptick in September, according to data collected by Associated Builders and Contractors (ABC).

The organization reports the nation's Construction Backlog Indicator, known as the CBI, reached 5.9 months in September—3.2% higher than in August. The backlog for the “middle states,” registered a modest increase in September of 0.2 months in backlog, or 3.5%, to 5.6 months.

The CBI measures the amount of construction work contracted to be completed. The indicator is published bimonthly and data are collected from ABC members on an ongoing basis.

In a statement, the ABC says that despite the CBI increase, the backlog remains “uncomfortably small” and, with the exception of the infrastructure sector, overall backlog “remains weak.”

The ABC attributes these results to the federal stimulus package and predicted that the peak of infrastructure spending, related to stimulus spending, will occur during the first half of 2010. On a regional basis, the average backlog for September rose in all parts of the country except in the South, where the CBI fell slightly—by 0.05 months in August to 5.76 months in September. That is roughly a 0.9% decrease.

The West had the largest monthly backlog increase between August and September—up 0.5 months to 6.3 months, an 8.1% increase.