A big day in New Zealand's industrial history..

Northland's Marsden Point shareholders are voting on whether to turn the country's only oil refinery into a terminal that imports processed fuels.

The union representing workers estimates jobs could be slashed from about 300 to 60.

Energy Resources Aotearoa Chief Executive John Carnegie says he's unsure which way the vote will swing -- but we have seen a pulp mill and steel mill shut recently.

He says we do seem to be exporting jobs and emissions overseas, so wonders if we're witnessing the hollowing out of our regional industrial heartland.