The Canadian arbitrator appointed to resolve a messy railroad labor dispute to protect the North American economy has ordered employees at the country’s two major railroads back to work so both can resume operating.Saturday’s order means Canadian National will be able to continue operating the trains it restarted Friday morning just over a day after it locked out workers. But Canadian Pacific Kansas City likely won’t be able to restart its operations before 12:01 a.m. Monday, when workers were ordered to return.Video above: AAA says domestic Labor Day travel will be up this yearRailroads play a crucial role in the economy with CPKC and CN delivering more than CA$1 billion (US$730 million) worth of shipments a day and carrying billions of dollars of goods between the U.S. and Canada every month. Even though both companies’ trains in the United States and Mexico continued operating, the lockouts caused a significant disruption. …