(Updates with latest developments)

Oct 1 (Reuters) - Dockworkers at 36 ports on the U.S.

East Coast and the Gulf of Mexico began striking on Tuesday,

halting container traffic in a stoppage that could cost the U.S.

economy billions of dollars.

The labor contract between the International Longshoremen's

Association (ILA), representing 45,000 port workers, and the

United States Maritime Alliance (USMX) employer group expired on

Sept. 30, as negotiations stalled due to disagreements over pay.

The affected ports process more than half of U.S. ocean

trade, and a widespread work stoppage would upend transportation

schedules, delay goods across a broad swath of industries and

send shipping costs higher. All of that could mean shortages and

higher costs for consumers.

Here's a brief rundown of key events related to the strike:

May 13, 2024

The ILA and the USMX say they will begin bargaining after

May 17 with the goal of forging a new deal before the current

six-year contract expires on Sept. 30.

June 10, 2024

The ILA halts negotiations amid disputes related to

automation, after discovering that operator APM's terminals and

container shipping company Maersk Line were using an Auto Gate

system that processes trucks without labor.

June 11, 2024

The USMX says some issues will require further conversation

between the local parties, adding that it looks forward to

re-engage with the bargaining committee.

July 12, 2024

Harold Daggett, ILA's president and chief negotiator, says

the threat of an Oct. 1 strike is growing after the violation of

its contract by some USMX members, which caused it to cancel

negotiations earlier.

Aug. 23, 2024

The USMX says it has been unable to secure a meeting with

the ILA to resume negotiations.

Sept. 5, 2024

Nearly 300 ILA delegates end their two-day wage scale

meetings with unanimous support for President Daggett's call for

an Oct. 1 strike if an agreement is not reached.

Sept. 23, 2024

The ILA says it has held multiple conversations with the

USMX in recent weeks and adds that a stalemate remains over

wages, with the employer group continuing to offer "an

unacceptable wage increase package."

Sept. 24, 2024

The White House says it will not try to broker a deal

between the two parties.

Sept. 25, 2024

Agriculture groups urge the White House to act to avert the

potential strike.

Sept. 26, 2024

The USMX files an unfair labor practice charge with the

National Labor Relations Board to bring ILA back to the

bargaining table.

Sept. 29, 2024

President Joe Biden says he did not intend to intervene to

prevent a port strike.

Sept. 30, 2024

The USMX says it raised its offer which would increase wages

by nearly 50%, triple employer contributions to employee

retirement plans and strengthen USMX's health care options.

USMX also requests an extension of the current master

contract to continue bargaining.

Oct. 1, 2024

The ILA starts strike at ports up and down the U.S. East

Coast.