The Canadian Union of Postal Workers may go on strike Friday. On Tuesday, the union gave a 72-hour strike notice. This means that Canada’s publicly owned mail service will slow its work — or potentially grind to a halt. Here’s what it could mean for Canadians.

Canada's postal workers could walk off the job or the company could lock them out as soon as 12:01 a.m. ET Friday if the union and the company don't reach an agreement. Here are tips for shoppers and businesses.

Should workers strike, the city said residents can contact 311 for details on how city services that typically use Canada Post will operate if there is a work stoppage. The city has also released details on how services could be affected if there is a strike.

From east to west, international shipments are at a standstill. Dock workers have been locked out at the Port of Montreal since Sunday. In British Columbia, they’ve been off the job for more than a week -- a dispute that Ottawa say has gone on too long.

The threat of a strike by Canada Post workers has small businesses in Waterloo Region feeling the pressure. It also has residents worried about shipments and deliveries ahead of the holidays. There was a steady stream of foot traffic going in and out of the Canada Post office on Bridgeport Road East in Waterloo Tuesday afternoon.