This brought total containerboard production for 2014 to 35.4 million tons, up 1.8% from a year ago.
US containerboard mills ran at 94.7% of capacity in December, up slightly from 94.3% in November and 90.3% a year ago, AF&PA reported.
Containerboard export production (mainly kraft linerboard) jumped 9.6% in December, resulting in a 6.3% increase for the year.
This was the "highest monthly export in more than 10 years" (excluding March of last year), according to Mark Wilde of the Bank of Montreal. Analysts said the jump in kraft linerboard exports was surprising given the strong dollar and slow global economic growth.
Mill inventories dropped 6,000 tons to 385,000 tons at the end of December from a month earlier, according to AF&PA. Mill inventories account for about 15% of total containerboard inventories at box plants and mills.
Fibre Box Association (FBA) will not release December statistics for box plant inventories and shipments until Feb. 2 when it completes its annual audit.