NEW YORK – Dockworkers along the East Coast and the Gulf of Mexico agreed Friday to extend their contract for more than a month, averting a weekend strike that could have crippled major ports from Boston to Houston and bottled up billions of dollars’ worth of cargo.

Talks aimed at reaching a new contract covering the 14,500 longshoremen will continue during the extension, which runs through Feb. 6.

The dockworkers’ union and an alliance of port operators and shipping lines agreed to the extension after resolving one of the stickier points in their negotiations, involving royalty payments to longshoremen for each container they unload.