Only seven states in the United States have a largest city with a population of under 100,000. Burlington, Vermont—the Queen City—is, by far, the smallest with a population of only 38,889.
According to Statemaster.com, Charleston, West Virginia, Cheyenne, Wyoming, Portland, Maine, Wilmington, Delaware, Billings, Montana and Fargo, North Dakota are the other six (in that order), but each has a population greater than 50,000. http://www.statemaster.com/graph/geo_lar_cit_wit_pop-geography-largest-cities-with-populations