ST. PAUL — The Green Line light rail that runs between St. Paul and Minneapolis is opening for business.

Service on the Green Line will officially start at 10 a.m. Saturday after a ribbon cutting ceremony at Union Depot on St. Paul.

Nine stations along the Green Line will host events including music and food throughout the day as part of the celebration — and all Metro Transit services will be free on Saturday and Sunday.

Large crowds are expected on opening day and trains likely won’t run on a normal schedule.

Metro Transit is offering a supplemental opening day bus service between light rail stations to provide additional transportation between events.