The union representing 50,000 Canada Post employees has begun a series of rotating strikes in four cities.

The 24-hour strikes began Monday at 12:01 a.m. ET in Windsor, Ont., and at 1:01 a.m. AT in Halifax, says the Canadian Union of Postal Workers (CUPW). Strikes in Victoria and Edmonton were also set to begin at one minute past midnight local time.

Mail and parcels won't be delivered or picked up in those cities while the rotating strike is happening, Canada Post said in a statement on its website.

Canada Post spokesperson Jon Hamilton said on Sunday that in the event of rotating strikes, normal mail delivery would be maintained in all other locations across the country.

While there won't be any delivery in cities affected by the rotating strikes, the delays are expected to be short. Mail delivery will resume the day after the rotating strike ends in that city, according to the CUPW.

"It's going to put pressure on Canada Post," said Nancy Dodsworth, president of CUPW's Edmonton local.

"But by doing rotating strikes, there is less impact to the Canadian public because we're still open for business, we're still processing mail, but things will just take a little longer to get through."

Striking Canada Post workers on the picket line in Halifax early Monday morning. (Brett Ruskin/CBC)

Tony Rogers, president of CUPW's Nova Local, said the union has been negotiating with Canada Post for 10½ months.

"We've done everything we could to try and reach an agreement, and they're not just getting it into their heads that we're serious about the things we've been discussing," said Rogers.

Job security among points of contention

The job action began after negotiators failed to reach a new contract agreement before the union's Monday strike deadline.

"Workers are genuinely angry with the corporation," said Rogers. "They've been insulted by the offers the corporation has put out and they're insulted by the fact the corporation hasn't been willing to move whatsoever on the key issues that we feel are important."

He said Canada Post has rural and urban units, and the issues for the two differ.

The rotating strike involves Canada Post workers in Windsor, Ont., Victoria, Edmonton and Halifax. (Darryl Dyck/Canadian Press)

For the urban unit, it has been "cash strapped" for 12 years because of "bad deals," wage freezes and wage increases below the rate of inflation, said Rogers.

He said the rural unit won a pay-equity settlement through arbitration, but Canada Post is negotiating as if the settlement never occurred or the corporation had won it.

Hamilton said Canada Post was committed to reaching a deal, and had an offer on the table that included wage hikes, job security, improved benefits and no concessions.

Uncertainty for small businesses

Small businesses called for a speedy end to Monday's rotating walkouts in four cities by Canada Post, concerned that a prolonged strike could bite into their profits ahead of the busy holiday shopping season.

The Canadian Federation of Independent Business also urged the post office to rein in spending to reduce costs and warned postal workers that job action would ultimately hurt them and their employer.

"While a rotating strike may be less harmful than a general strike, it creates additional uncertainty for businesses at a critical time for many small firms," CFIB president Dan Kelly said Monday in a statement.