While most of MDT's programs relate to the state's highway network, Montana's railroads and airports are also under the agency's purview.

The responsibilities of the department include:[1] In March 1913, a state Highway Commission was created by the legislature, consisting of three members.

The passing of the Federal-Aid Highway Act of 1956 gave major funding to the department and required it to be greatly expanded.

The Transportation Commission's responsibilities include selecting projects, awarding contracts, designating roads to highway systems, and resolving outdoor advertising issues.

The Aeronautics Board has authority over airport loan and grant funds and advises the rest of the department.

The money is put into the Highway State Special Revenue Account and can only be used for transportation related purposes.

Increasing costs outpacing current revenue is causing the department to fall behind on maintenance of infrastructure by $1 billion each year.