The Maine Department of Transportation, also known as MaineDOT (occasionally referred to as MDOT), is the office of state government charged with the regulation and maintenance of roads, rail, ferries, and other public transport infrastructure in the state of Maine.

It also monitors environmental factors that affect the motor public such as stormwater, ice/snow buildup on roads, and crashes with moose.

MaineDOT owns hundreds of miles of railway track in the state, much of it acquired as the result of abandonment of rail on unprofitable lines by private carriers.

[7] The law also provides for the Maine State Ferry Service Advisory Board,[14] which is charged with advising MaineDOT on all ferry-related matters and recommending changes via an annual report, as well as naming MaineDOT's ferry vessels and terminals.

[16][17] Besides MaineDOT, coastal Maine is served by a number of other private and public ferry operators.