(Reuters) - Canadian National Railway and Canadian Pacific Kansas City have locked out workers, starting Thursday, after unsuccessful negotiations attempts with a major labor union.

The workers, represented by Teamsters Canada, have been negotiating since the expiration of contracts in December 2023.

The stoppage has halted movement of grain, potash, coal and other commodities across the country's extensive freight rail.

Here is a timeline on the negotiations between the parties:

Date Events

Dec. 31, Contracts covering locomotive engineers,

2023 conductors and yard workers at CN and CPKC

expire.

Feb. 19, Teamsters claim that CN and CPKC are "not

2024 serious about negotiating and avoiding a work

stoppage".

May 1, 2024 9,300 railway workers at both companies vote

to strike as early as May 22.

May 10, The Canadian government says it is moving to

2024 push back the start of a possible strike by

railway workers.

May 16, CPKC says its leadership, with the assistance

2024 of federal mediators, will resume negotiations

meeting with Teamsters on May 17.

May 23, CPKC says talks have hit a deadlock,

2024 predicting that a legal strike or a lockout

would not likely occur before mid-July.

June 7, The union says CN and CPKC rejected a proposal

2024 to stagger negotiations with both companies by

two weeks.

Aug. 5, The companies and union restart negotiations

2024 along with federal mediators, says Minister of

Labor Steven MacKinnon.

Aug. 9, Teamsters warns a work stoppage could start on

2024 Aug. 22 if a deal is not reached.

Aug. 9, The rail companies say they would lock out

2024 employees on Aug. 22 if talks to negotiate a

labor contract fail.

Aug. 15, Minister Steven MacKinnon rejects a request by

2024 CN Rail to initiate binding arbitration.

Aug. 17, CPKC says will halt any new rail shipments

2024 originating in Canada, and all new U.S.

shipments destined for Canada starting on Aug.

20 if talks fail to progress.

Aug. 18, The railroad operators issue lockout notices

2024 to workers represented by the Teamsters union.

Aug. 19, Labor minister says he will meet with both

2024 companies and the union in Montreal to avert

stoppage.

Aug. 22, CN and CPKC shut down their rail networks in

2024 the country and lock out nearly 10,000

workers.

(Reporting by Aishwarya Jain in Bengaluru; Editing by Sriraj Kalluvila)