The Maine Narrow Gauge Railroad Co. & Museum is a narrow gauge railway, located in Portland, Maine, United States.
Operating out of the former Portland Company Marine Complex, the organization was founded in 1993. The collection consists of passenger and freight equipment, as well as artifacts from the narrow gauge railways that ran in the state of Maine in the late 19th century and early 20th century.
The organization operates a long railroad that runs along the waterfront of Casco Bay and parallels Portland's Eastern Promenade. Historic steam and diesel locomotives and a variety of restored coaches are used to run passenger services on the railroad.
In 2014, the railroad planned to move their equipment and relocate to Gray, Maine with a brand new depot and engine house building planned to be built; however, the plan never came to fruition and the museum decided to remain in Portland.
In 2021, several of their steam locomotives were on long-term loan at the Wiscasset, Waterville and Farmington Railway.
In mid-January 2025, the railroad was shut down for several months as tracks were ripped up for "Portland Foreside", a $660M luxury neighborhood development project, featuring a hotel, restaurant, condos, apartments, as well as an indoor market and public plazas. MNGX originally expected the railroad to be down for two weeks while the tracks were removed and replaced following construction; Foreside claimed the construction was planned to minimize disruption.
Each year beginning in November and continuing until Christmas, the Maine Narrow Gauge operates The Polar Express excursion train based on the 2004 film The Polar Express and the book of the same name. The train is the largest fundraiser for the nonprofit train museum. In 2023, 23,000 passengers rode The Polar Express train. The train ride includes a visit from Santa and chefs serving hot chocolate and cookies.