The city of Bismarck recently built a new airport facility. I have not personally flew out of Bismarck in a few years, but I have heard people rate it favorably compared to flying into other airports in the United States.
Bismarck public transit system is called the "Capital Area Transit" or CAT. Routes are available through out Bismarck and the sister city of Mandan. The buses are NOT available after 6:30 PM. There is limited route service on Saturdays and no service on Sundays. 30-day passes are available as well as per-trip fees. Fees for children and seniors are very inexpensive. Transportation for the handicapped are also available.