COLUMBUS, Ind. — Factory shipments of commercial trailers hit their lowest levels since 1978 last year, according to ACT Research.

The highest monthly total of 2009 came in December, when 8,296 factory shipments were made. Full year shipments were 44% lower than the year before, according to the State of the Industry: US Trailers report, published by ACT.

The industry forecaster said virtually every category of trailer posted its lowest total shipments in 30 to 50 years. Only the reefer van sector held up relatively well, ACT reports.

The good news is, net orders for commercial trailers were up 140% year-over-year in December.

“Reaching a 32-year low required not only the worst economic downturn in generations, but also the impact of trailer tracking technology on trailer productivity and utilization,” said Kenny Vieth, partner and senior analyst with ACT Research. “On a more positive note, inventories reached a new four-year low, a prerequisite for improvement in production rates.”