Boston city councilors got a chance to explore a proposed commuter rail tunnel linking North Station and South Station at a hearing Monday.

Called by at-large councilors Michelle Wu and Annissa Essaibi-George, the hearing on the North-South Rail Link featured presentations by former Gov. Michael Dukakis, activist groups including Transit Matters and the Sierra Club and members of North Shore’s U.S. Rep. Seth Moulton’s office.

Proponents say the tunnel will enable the MBTA to run the kind of frequent rail service to suburban communities needed to draw commuters off the roads, and will help break down the north-south divide in the region’s workforce enforced by the current commuter rail system, in which two separate train networks terminate at North and South stations.

Gov. Charlie Baker opposes the idea, preferring an expansion to South Station’s platform areas.