The automobile industry is the largest US importer of goods shipped via container transport from Japan, giving auto manufacturing and support businesses the greatest threat of disruption as Japan’s industrial output struggles following the devastating earthquake and tsunami, according to data and analysis from The Journal of Commerce/PIERS.

Japan is the No. 3 exporter of containerised goods to the United States, according to PIERS data, behind China and Korea. The country is second, behind only China, as an importer from the US, based on container volume measured by PIERS data.

Although three Japanese ports – Sendai, Hitachinaka and Kashima – have remained closed since the disaster on the northeastern coast, the country’s largest ports, including Tokyo, Kobe and Yokohama in the industrial southern part of the country were open this week and handling commercial vessels.

But Mario Moreno, economist for The Journal of Commerce, said Japanese exports “will weaken in the months ahead as the closing of several manufacturing plants prompted by electricity shortages, combines with severely damaged roads and bridges to hamper production.”

In 2010, US containerised imports of auto parts from Japan, accounted for 28% of the total US imports of this commodity globally.  Boosted by solid gains in US auto sales last year, imports of auto parts from Japan rose 22% in 2010, according to PIERS data. The increase was already slowing in 2011, growing by only 3%, year over year in January 2011 versus 2010.

“The positive trend is unlikely to continue,” says Moreno.  “US car manufacturers, like Toyota, must meet strict specifications and use Toyota-made auto parts only.”  Moreno’s forecast issued in December anticipated a 2.5% decline in US containerised imports from Japan, coming off high volumes in 2010.

Japan’s bilateral trade includes China as its top export market, with 21% of its total exports in 2010, while the US accounted for 17%.  Japan’s export to China was US$598bon in 2010, up 36% from 2009, and exports to the US totaled $482bn, up 26% from 2009.