Signs of an improved housing market have been matched by some improvement in the number of jobs in construction in Minnesota, but there's one sector of the construction industry that, in the aggregate, is not hiring.

In September, 13,184 people worked in heavy and civil engineering construction in Minnesota, a 20 percent drop compared to 12 months earlier.

The numbers will be revised when they're benchmarked against the more reliable quarterly census of employment, but officials at the state have noted the sector's weakness.

“The one area that continues to be a drag on the sector is the heavy and civil, the roads, bridges and light rail construction,” said Steve Hine, a labor market economist for the Minnesota Department of Employment and Economic Development. “That continues to be a weak spot.”

Why this is a weak spot is a little more difficult to pinpoint.

It could be that infrastructure projects paid for by the 2009 federal stimulus bill are winding down, though a spokesman for the Minnesota Department of Transportation said DOT construction spending has been fairly consistent over the past few years. The League of Minnesota Cities has a list of more than 150 delayed or canceled projects in 2010 to 2011, but the list is anecdotal.