According to the 2010 Census and subsequent updates the population of Butler County is 12,827 (2011 estimate). By way of comparison the 2012 Census update set the total population of the United States at 313,914,040. Kentucky ranks 26th on the list of states by population, with 4,173,405 residents. California is the most populated state in the union with 36,132,147 citizens. Wyoming has the sparsest population with 509,123 residents.