Texas’ largest public transit system is set to launch service on a $2.1 billion commuter rail that will connect seven cities across the Dallas area after years of delays.

Dallas Area Rapid Transit is scheduled to start running the Silver Line on Saturday, a 26-mile corridor linking Plano, Richardson, Addison, Carrollton, Coppell, Dallas and Grapevine with Dallas-Fort Worth International Airport’s Terminal B. The project, first conceived decades ago as the Cotton Belt corridor, marks the agency’s largest capital investment to date and a rare east-west connection that doesn’t run through downtown Dallas.