Residents in Washington State took to the polls on Tuesday to vote on a proposed bill that would require manufacturers to label any genetically modified ingredients on product packaging.

The fight over GMO labelling has become the most expensive food fight in the state's history, with genetic engineering companies like Monsanto providing $23 million in opposition to the bill.

But Nature's Path Organic in Richmond, B.C., gave $250,000 to groups in support of the bill. The company's owner, Arran Stephens, says that a 'yes' vote in Washington would cause a "ripple effect" and ultimately encourage GMO labelling in Canada.

Voting results are expected Wednesday afternoon at 2 p.m. PT.

With files from CBC's Kirk Williams