Wage gains in Canada are trailing behind rising food prices, a major force driving the labour strife that has upended the country’s supply chains.

In the span of four months, the northern nation has been rattled by work stoppages involving key infrastructure. Prime Minister Justin Trudeau’s government forced railroads to start moving again in August and sent dockworkers in Vancouver and Montreal back to the job earlier this month. Now, postal workers are striking just as the holiday season begins.