Answer:
It all depends on what you determine major cities to be.
South Dakota's most populated City is Sioux Falls at 153,888 residents.
The second largest city, at 67,107, is Rapid City.
Aberdeen ranks third with a population of 24,992.
Aberdeen, Watertown, and Brookings all have populations between 20,000 and 30,000.
Pierre is the state capital with a population of 14,072.