The National School of Business was established in downtown Rapid City in 1941 with a curriculum that offered secretarial and accounting classes along with other specialized business training. Through World War II and the Korean War, the university remained in its original location.

Anticipating a post-war demand for business education, administrators planned a business administration curriculum with new classes in accounting, marketing, management, and programs geared toward the educational needs of returning veterans and others who wanted training and an expanded role in the business world. In 1960, ground was broken at 321 Kansas City Street for a new two-story brick building containing classrooms, a bookstore, a small library, and administrative offices. The College Inn residence hall was completed in 1963.

Faculty and staff increased in number and, with the school’s growing stature in the educational community, new and transfer students from across the United States and foreign countries came to study. The college soon expanded its base of programs, and the name was changed to National College of Business. Later, due to its branch expansion into several other states, the campus and branches were joined under the banner of National American University.

Campuses have been established in Colorado, Kansas, Missouri, Minnesota, Indiana, New Mexico, Oklahoma, and Texas. There is also an extension location at Ellsworth AFB, South Dakota.

In 1996 National American University began to develop courses available on the emerging resource of the World Wide Web. Since that time, the NAU Distance Learning program has created a virtual campus offering degree programs in several academic areas.

With the addition of on-line course offerings and degrees, students now have access to learning 24-hours a day from anywhere the Internet can be accessed. Curricular offerings include accounting, general studies, information technology, legal studies, medical assisting, business administration, therapeutic massage, athletic training, health care management, pre-engineering, organizational leadership, and veterinary technology.

NAU is accredited by the Higher Learning Commission and is a member of the North Central Association of Colleges and Schools.